So you have a guild to lead? How you run your guild is up to you as long as members follow the game policies. However, here are some tips written by an experienced guild leader that you might find useful.

Create Guild Rules
Come up with a list of rules for your guild. Make them available to your guild mates via a web page, if possible, or you can pass them out via email. Many common problems can be solved by coming up with rules and making sure everyone is aware of them. As various issues come up, you can simply update the rules as you go. The rules need to change with the times and the guild. You can consult with officers to think of rules that should be added or modified before posting them for all members. Most people are fine with rules as long as they are public and easily accessible. Remember, it's good to make sure your members are aware of the game policies.

Select Good Officers
Select good co-leaders for your guild. These players need to be able to control the guild while you're not around. It's common to select your closest friends for this role but they are not always the best choice. Some good friends don't make good leaders. For the best results you need people who can lead and arbitrate disputes. It really depends on how large your guild is. If your guild is a close group of friends this may not be necessary. However, if you have a large guild with players whom you may not be personal friends with in real life, then you might find that good officers are a requirement.

You can create your own ranks and define rank permissions via the guild management controls. This allows you to start officers off with some basic commands. You are then able to reward them with more if they earn them through good leadership.

Guild Officers should be in regular contact with each other via the in-game officers' channel, forums, email, IRC, or whatever method you prefer. They need to discuss events and issues as they come up and figure out solutions.

Reward Good Behavior
Reward good behavior in your guild by increased power. You can create special ranks for your guild that players can earn through whatever deeds you deem necessary. Just as players wish to upgrade their characters, players also wish to improve their status in the guild!

Punish Bad Behavior
You can punish bad behavior in your guild by having a leader talk to the person causing trouble. Remember that a threat to remove them from the guild is always a good way to improve their behavior. Another option is to create special ranks in your guild that are identified as punishment. You can then reduce the permissions for that rank to virtually none (i.e. - unable talk in guild chat). When players have served their punishment you can reinstate their powers by upgrading them back to their previous rank.

Item Disputes
Item disputes are the most common source of conflict in a guild. Sometimes players get greedy and fight over the same item in a party if they both want the item. Create rules, and make them public as to how guild members should respond to this situation. You can also refer them to the guild leaders to help determine what should be done. Otherwise, item disputes can explode into huge fights with people taking sides. A good thing to remember is the "/random" command. You can type "/random 1 100" to generate a random number between 1 and 100. Then whoever gets the highest number wins the item. This is a common method used for determining who gets an item if multiple people want or need that item.

Guild Chat
Guild chat can sometimes get out of hand if you do not manage it. You can tell people in the channel to settle down. You can also demote a bad member in the guild to a level that doesn't allow them to talk in guild chat until they improve their behavior.

Inactive Guild Members
You might want to create a policy that removes guild members that are not active in the game. This is up to you. It's not really hurting anything to allow them to continue to be in the guild, but it doesn't encourage other players in the guild to play. It also takes up room on the guild roster.

Create a Guild Web Site
Most guilds do this. If you don't know how to create a guild web site, find someone or invite someone to your guild who can.

Create Guild Forums
Create your own guild forums. Guild forums allow guild members to discuss the guild and the game in a format that is more long term. Just make sure you have good forum moderation and make it clear what is not appropriate to post. Guilds usually keep all or some of their forums private so that other non-guild members cannot disrupt or troll your forums. You also may not want to share information on how your guild works, your raid progress, or your raid strategies with other guilds.

Guild Tabard
Have everyone in the guild contribute to the purchase of the design for the guild tabard. That way you can afford it much sooner. You may also wish to involve the guild in the decision of the design of your guild tabard. Higher-level guild members can also help lower-level members purchase their guild tabard since it is expensive.

Trade Skills
Sometimes it's better to pick one person for each trade skill that is specifically responsible for being the best at that skill. When a bunch of people are doing the same trade skill, they compete against each other, and this doesn't benefit the guild. You will probably want to have some backups just in case the main trade skill person is not online.

Let everyone in the guild know what trade skill items and recipes they should collect and whom they should give them to.

If the guild works together, its trade skill craftsmen and the entire guild can benefit.

Gathering System
Create a gathering system for the guild. This includes gathering herbs, mining, and gathering materials needed in trade skill recipes.

Find a Player Bank - Step one is to decide where to send these gathered materials. You can pick a specific player or create a new one. Sometimes guilds create an alt (level 1 character) used for mailing/gathering. An example would be a player creates an alt named GuildNameAbreviationHerbs: PDHerbs. Inform the guild members to mail all donations to that character. Then a player is responsible for reading the mail, storing the items, and redistributing them. Obviously, you need to pick guild members you trust with 100% certainty to control those guild bank characters.
Record all donations - Release reports with rankings of donations listing the top donators and how much they've donated. This makes them feel good and creates a competition between gathers. Some will work harder to increase their rank on the list.
Reward Donators - There are various ways you can reward donators. You can promote them within the guild. A good donator shows loyalty to the guild. They could easily sell their donations on the auction house instead of spending time gathering for nothing for the guild. You could reward with preferential loot treatment or invitations to raids. You can think of something.
Get members their Epic Mounts
Create a system that allows the guild to help members get an epic mount. An epic mount is very important for PvP and for saving time getting to raids. If the guild buys or helps pay for a member's epic mount they'll be much more loyal and appreciative toward the guild. It won't work on everyone but it will work on most players. You can have other members help donate to a mount fund. Maybe they receive some sort of credit for donating like a bonus to a chance to gain raid loot. You can ask that members repay the guild's cost for helping them get their mount.
Pool Money
If there is something that would be especially helpful to the guild, pool money together from members and buy it. This can allow you to buy things that wouldn't be possible to buy otherwise.

Helping Guild Members
If you find an item that you don't want you could sell it at the auction house. Or, you could give it to other guild members that might need it. Offer it to people in the guild chat channel. Meet up with them, and give them the item. This can really improve relations between guild members, as well as assisting the guild as a whole.

Quest Completion
Some quests require raids to complete. Set up a specific time in the week or every other week when the guild can come together to help people finish raid quests. Sometimes a good time to do this is after or before a scheduled dungeon raid (Molten Core/Blackwing Lair/AQ/Naxxramas).

Guild Events
Guild members enjoy planned events. Notify members ahead of time when an event is going to happen, and make sure you have strong leaders to run the event. A common event is to attack a specific location with your entire guild. These gatherings also give a chance for players to exchange items for trade skills or give hand-me-down items to lower-level guild members.

Recruits
Recruit needed classes for your guild. Start out recruits on temporary member or recruit status. Take them on raids and see how they do. If they do well, invite or promote them to full membership. If they don't do well, say it didn't work out (but remember to be nice!) and send them packing. If they happened to donate anything in this short amount of time, it's nice to return their stuff. But donations are also just that, donations, and there is no obligation to return them. You might want to have a somewhat long recruit process (weeks - month) so that you can be sure the person is a decent player and will fit in your guild.

Trust
It's very important that you be able to trust your guild members. If they do something that shows they are not trustworthy, you may want to remove them from the guild. There are many opportunities within a guild to take advantage of the guild or to possibly steal gold or items. If the player is not trustworthy, they might take advantage. Many guilds remove players that demonstrate a lack of honesty.

Main profession tradesmen and guild treasurers require a LOT of trust. Do not assign these positions without knowing for sure if the players are trustworthy.