The most common one for me is soloing, you wander around trying quests, or 'grinding' killing creatures and enemies (mobs) for experience and treasure (drops).
Then there's duo play, you and one other person. My most common partner is ocaeron and his Night Elf Warrior. We work well together, we know how we both play the game, and we enjoy it. It's not very fast though, as our character combinations (Druid and Warrior) don't allow for it. We play it as most people would, Lee doing the fighting, me keeping him healed and being the secondary attack, but as Warriors are more about endurance than destructive power, we tend to have safe but not too fast kills. If Lee dies, things went very bad, and I've probably already karked it. We play other characters as well, his Priest and my Warrior (a smiliar experience to Malreth and Isilme, just reversed roles), and both our Mages together (things die VERY quickly, but we're also VERY fragile).
My next most regular partner is Fleece, a Night Elf Hunter. I don't know her rt, we just met in a quest back at the beginning, and we've been mates ever since. She knows more people, and has recently managed to gain more experience than me (she concentrates on a single player, whilst I have several). We work fairly well together, although it can be a bit strained recently, foe example, we were in Un'goro on Sunday, when 4 mid-50 level mobs attacked... I'm level 49 at this point, I can take these on individually and win, if I play smart, but 4 of them, no way in hell) She hasn't got aggro over all of them(another in-game term; mobs attack those which present the biggest threat to them, and flashier moves gain more threat. My healing spells for example, the better ones are like bonfires to a moth. It's a fine art, managing aggro, and it's what the Warrior is best at, they should actually try to attract it, as they have the best armour and highest health, which means they can take the hits whilst every one else is fighting, something called 'tanking', which can apply to any one who fulfulls that role. As Fleece can now wear mail armour, and I'm stuck with leather for ever, it should be her and her pet who take that role, which she does try, but it's not a Hunter's speciality... so the second I tried to heal her, 3 of these bastards were on me, my health was fading rapidly, I was in trouble. So I did the only thing I could, shifted into cheetah form, and ran! No it's not a terribly brave thing to do, but it's better than dying. She thought I was abandoning her, so I had to point out the differences that a 5 level gap presented. But we're usually cool, have a laugh, do a bit of questing, it's cool.
The latest addition to my circle of adventuring buddies is Lee's friend James, who plays the head Rogue in our Guild, and is currently the second-highest level (after me..) and is likely to be the highest soon as he doesn't have to go to work! The tactics for us working together are similar, but different from Lee and I. With Lee, I can be more active in the attack-front, but with a Rogue, they sacrifice staying power for damage-dealing. Things die a lot more quickly when a Rogue is attacking that any one else in close range, but they also only have leather armour and a less-than great level of health. SO Itend to leave the damage dealiing to him, and focus on keeping him alive. It's quicker, but more risky (I can only cast so many spells due to their mana cost, and all but one take time to cast, possibly made worse if I'm being hit, delaying the casting, or even interrupting it entirely)
Next up is the party, 4 or 5 people all grouped together, which usually happens for the more difficult quests. Many people consider the perfect combination to be: 1 Warrior (to tank), 1 Mage (long range damage), 1 Rogue (close combat damage), 1 Priest (healer) and another, healing capabilities a plus. I've never been in a group like that yet! Doesn't help that my main character isn't one of those classes of course... but being a Druid, I can play all of those roles to differing degrees of success! Many even say that the Druid is just as good a healer as a Priest, and I've only ever had one complaint about the healing I bring to a group, and that was from some one who seemed to forget I had mana and casting-time issues. You basically work out what roles a person will play, and usually it's easy to do so. A warrior is going to tank, a Rogue's going to sneak attack, a Mage will do damage with spells and so on. But with more hybrid characters like Druids and Paladins, more options open up. A Paladin can tank, and act as a secondary healer, even primary healer if you've got no choice. A Hunter can have their pet tank, and provide te ranged damage themselves, and so on. It's when you get bizarre groups (like say 4 Rogues and a Warlock) that initiative is required
Then there are raid groups, a collection of 5 man parties used for stomping over the lands of the opposing faction, or for taking on the infamous quests to kill off dragons etc. The only time I've been in a raid group was for a beach party. Less said the better.
So it really does depend on what classes you have available, as to how you play the game. Certain classes are what you would call primary, they specialise in one area;
Warriors are there to take hits and dish out fair damage. Rogues are there to be sneaky and deal insane levels of death. Mages are best at raining down all kinds of hell upon their targets. Priests can hurt, but they're better at making sure the others aren't.
Then there are the hybrid classes, the ones that can do bits and bobs;
A Paladin can tank almost as well as a Warrior, but also has the ability to cast a few spells, provide a few buffs (things like spells that give long time benefits to other, like an increase in a stat)... The Hunter and Warlock are similar in that they can provide long range support, but they also have a companion that can help as well (I love grouping with either class, as you get a free group member), the difference being that a Hunter is better off in close combat than a Warlock, but a Warlock can debuff enemies more (debuffing is the opposite of buffing, obviously, think of it as cursing). I've not got a lot of experience with Shamans, but they seem to be pretty good all round. I have a hell of a lot of experience with Druids obviously, and they can do pretty much anything to some degree. Need some one to tank? Let me just shift into bear/dire bear form. Need some one to be sneaky? Why the cat form is best for that! And I have spells that can cause damage and heal as well! Druids also get some good buffs and cures, including Mark of the Wild, the best buff in the game. Druids should be welcome any where!
As well as primary and hybrid characters, there's another distinction, that some are 'support' classes. These are the groups that can focus on helping others, a Warrior is not really a support class, but the Priest standing back and healing him is. This only really comes into play when you're in a group. A Priest should concentrate on support duties, but if she's in there focusing on melee, she's not really using the skill sets to the best advantage.
So where's this leading to? Last night when I got home from the theatre, I once again set foot within the troll temple that has thus far foiled my attmepts to conquer by putting me in a group that dissolved the first time, and the second time influencing Audrey to invite me to Green Day. Tis truly a wicked place. James invited me, and there were already two Hunters in the group. So 1 Rogue, 2 Hunters and a Druid. Pretty easy to work out, the Rogue does sneaky and damage, the pets do the tank roles, the Hunters provide ranged cover and melee, and I stay back providing support, buffs and healing. When you join a group, it's considered good manners, and logical, to buff all your companions (and pets if applicable). So I turn up and start spreading Mark of the Wild and Thorns like they're going out of fashion (this can be very taxing on your new friend Druid, so do the decent thing and let his mana regen afterwards before launching into battle). And then a new member is added to our group, a higher level Druid. Fair enough, Druids are damned handy, and we now had 2 capable healers! So she turned up.. and buffed no one. Her bufs are a higher level than mine, they give better bonuses.. but she didn't share them. Nor did she heal, leaving that primarily to me, even though her spells are better again. When I asked her how she wanted to manage who did what, she ignored me, so I had to be watching what she was doing, and respond to that. Okay, so you're in dire-bear, guess I'm supporting then eh? Not healing him? Shall I do it then? I was not impressed! At one point we got mobbed in some caves, and she died. Not to worry, the Druid can resurrect their fallen companions, though the spell does have a 30 minute cool down period before you can cast it again. So the fact she even managed to fuck that up (all she had to do was click 'yes' in response to the message that I wanted to resurrect her, would she accept) made me even less endeared to her. She just wasted a spell I might need later on, and a physical component required for the casting! However, when I died, she manged to cast her rez spell correctly, and I didn't mess up my part, so I guess she wasn't utterly useless. By the end she did start buffing people, but it shouldn't have taken that long. She was 7 levels higher than me, it should have been automatic that she took the primary role, and I was support.
Some groups gell together well, and almost immediately. Every one works out their roll, works out how the others are playing the game, one person starts to call the shots to avoid confusion, and they stay together and watch each other's backs. That's the play I'm used to, that's how it is when I play with Lee, Fleece and James, individually or as a group. So I really hate it when I get grouped with people who have no clue. What kind of arse-hat makes the call 'every one mount up and make a run for it' when you're at the top of a troll temple, all the mobs below have respawned? If you're going to do that, you stay together, you support each other, not every one for themselves. 2 people died trying to get out, it was nearly three but I noticed one of the Hunters was getting extremely low on health, so I sprinted back to help him (PAST the other Druid on the way I might add). The group dissolved rapidly after that until it was just James and I, and we were only using it so we could chat more easily, whilst he went off elsewhere and I stayed in the area to grind.
If nothing else, I at least managed to achieve the point of the ascent, and it got me close to levelling up... but it also highlighted why I hate grouping with random people.. you never know what level of quality you're going to get.