Mynia, of Archetype X, wrote a really good post on the ideal qualities of a raiding guild. As the thread will eventually disappear into the void, I'm reproducing it here.
Here are the most important things for me:
1) The people should be polite and respectful. Cursing is fine as long as you aren't cursing AT someone. If you respect the people in your group and know they are doing their very best then there is no need for the stereotypical yelling etc. If they aren't doing their best rethink if they should be there.
2) No hotheads please. The worst thing about raiding is it sometimes is stressful. You are spending hours wiping repeatedly on bosses to learn the encounter. Everyone needs to be mature enough to step away when frustrated. With the right attitude and respect for others even wiping for hours can still be fun and challenging instead of miserable. A good sense of humor also helps here.
3a) Everyone should be on time and prepared. 39 other people are waiting on you and for many people game time is valueable. If we are starting at 6 show up before 6. Not at 6 and not after 6.
3b) The raid leader should begin the raid on time, even if everyone isn't there. Most instances you can clear trash etc without the entire 40 present.
3c) The raid leader should also end the raid on time. If the raid is supposed to end at 10 then end it then. People need sleep and if raids run too long it hurts everything. Tired people are not as sharp and reflexes get slower. Tired people also might be late to work/school etc making said person unhappy in RL and make them not want to raid with you.
4a) The recruiting process should be a long one. If your group is close knit and spends hours and hours raiding you need to be sure that this person wants in for the right reasons, fits the personality of the guild, has the same goals in game, and their RL schedule works with the appointed raiding times. Applications, causal instancing, trial runs, and then probationary status are all good ways to confirm if someone is a good fit. If it takes 3 weeks then it takes three weeks.
4b) Part of this process too is determining if the person understands his class well. Find out how they are specced and ask questions. Let them defend their build. If they know there stuff and put thought into it then they should do well.
4c) Look at their gear. Is it a random hodge-podge? Their gear is an indication. A motivated individual will spend their time farming good gear with stats and abilities that complement their build.
4d) Asking questions about alternate characters and knowledge of other classes is also a good thing. Playing other classes broadens your knowledge of the roles and importance of the other people in the raid and how they all work together. This is important, as the raid needs to work smoothly together and understand everyone elses role.
5) Your Guild.
5a) Don't overwhelm your guild with tons of people and don't over fill your classes. There is nothing more frustrating than having to sit out of a raid because there are like 100 people and only 40 spaces available. If you spend the right amount of time recruiting you shouldn't have issues with low attendence etc.
5b) Guilds with "mixed" types of players are more difficult to manage and its hard to make everyone happy. Stick to one focus if you want to raid. Everyone or 90% of your guild should be raiders.
5c) The rules of the guild should be clearly written and posted somewhere for reference. This includes recruitement processes, guild goals, processes for displinary action, attendance requirements, loot distribution rules, raid times/schedules etc. Miscommunication and undocumented "rules" are often points of contention.
6a) Stratages are fine, but if you use them be careful. Nothing adds more chaos to a new encounter than changing the strategy that everyone has studied mid fight. Be sure that everyone knows what the strategy for your next boss fight is and that everyone has read it. Have a plan B strategy as well, if the first plan really isn't working for you.
6b) There is no law that says you must beat the encounter the way that everyone else does it. Find the way that it works for your group and do it that way.
Those are the highlights anyway for me.