You can have a set of rules that works great for your guild. And if you have only 1 raidgroup within the guild you can expand the guild rules with raid rules. In my guild we ran Naxx25 with 2 groups, and had 4 10mans running it. We now have several groups running Ulduar, and we have a subset of rules within each group, as well as overall guild rules.
10 Things to think about when setting up Raid Rules.
When you form up as a raid group it is important that the initiator lies down the first set of rules, and maybe these aren't even so much rules, but more general goals that the organizer wishes to achieve.
If you organize a raid with the goal of beating new content in Ulduar, and you find yourself with a group of raiders who just want to do Naxx for the fun of it, neither the raiders nor the organization will be happy.
2. The Road
Make sure that you also think about how you wish to achieve these goals.
Wordy Warrior mentions in her blog post that they sometimes "purposely let people die for laughs." In my book that wouldn't be fun at all, but I know that one of our other raid groups finds it completely hilarious as well. I would be completely annoyed with people every time this happens.
Different people need different approaches and before everybody gets very pissy with each other about how things are organized and done, it is best to make clear how the raid will be run, and make sure that people who run in that group are agreed, or in the least ok with it.
3. Meet in the Middle
If you don't have all noses pointing in the same direction, then make sure that you can at least come to a general agreement.
One part of your group wishes to do Naxx10, the other part wants to do Ulduar, agree that you will do one today and the other the next time. If you cannot unite the two parts into an agreement then don't start the raid group. You will simply make people unhappy and it is doomed to fail.
In a lot of cases in WoW you will find that raidleaders are the ones who took the initiative to get a group together. However, you generally need more than just one leader, you also want a lead tank, a lead healer, and a main assist.
Often these roles are filled in a natural way when people who are suitable to do this either prove themselves during raiding, or when they step up to fill the role. Don't try to hurry finding your leadership, if people just aren't right for the job it's no use forcing it onto them. If you have to, or the situation calls for it, then try to make it a temporary situation, since in the end neither the leader, nor the rest of the group will be happy with it for too long.
Make sure that you know why your raiders are raiding, and set up a loot system accordingly. One raid group can be perfectly happy with free roll and trusts everybody to have a sensitive mind about it, and the other group can feel the need for a more structured loot system like for example DKP.
One big thing that you want to prevent here is that loot becomes the reason for problems later on. My opinion in this?
Loot is to progress in raiding, it is not an objective on its own.6. Left Out
Being asked to sit is one of the shittiest things to experience. For those who have been asked to sit, I can assure you that the other side, the actual asking, is at least as horrible. However, if you have 11 people for 10 spots the game simply doesn't allow you to bring all of them.
7. Performance & Preparation
It is important that everybody in the group is aware of what is expected from them performance wise. I know that for my guild there have been situations in the past where people were addressed on their performance and they didn't even know they were doing badly, because they had no idea what was the expectancy.
Some raid groups expect everybody to do their own farming, others have a guildbank that provides, and others do it within little groups. In the end it is important that people know what prepared means, because they can show up and be all ready to raid in their point of view and still have gear ungemmed.
If 9 of your 10 people are cussing like saylors, and the 10th cannot stand swearwords you can bet on having a group of 9 soon if people aren't aware of this. If half of your group is always strictly on time, and the other half is always late you will also have an argument on your hands.
Make sure you follow your rules. If they need adjusting then adjust them officially, and follow them again. If people don't follow the rules they have accepted by accepting the invite to the raid then this should be pointed out to them, and if this doesn't help harder measures should be taken.
Protect your raidgroup from running sour by just letting things slip. Once you have rules, those rules are there for everybody, no exceptions.
I often think that PuG groups are like M&Ms. If you stick your hand into a bag of M&Ms blindly and pick out 10 of them, you're likely to get different colours. And sometimes these colours go great with each other and sometimes you get a blue in between all the brown and yellows.
Still you can try to get the objectives clear as much as possible, and try to get a group of people that does complement each other. All you have to do is keep your eyes open when you take the M&Ms out of the bag.