So, You want to start a guild? First things first, let's get some decisions made.
Type of guild:
There are several types of guild you could be;
Social
Hardcore Raiding
Casual Raiding
PvP Battlegrounds and Premades
Arena Players guild
Leveling guild
After determining first of all what type of guild you want to be, we will move on to the next step.
So, you want members, how do you go about it?
Well this scales mostly on the server you're on, if you're looking to start a social or leveling guild, it won't matter too much as you have a much wider target audience.
If you're looking to start a Pvp guild or Arena guild, it's best to find out what server has the highest interest in PvP, for example stormscale horde on the european servers has the widest range of players interested in PvP, you can find this out using your battlegroup forums or heading to an unofficial site like Arena Junkies - World of Warcraft PvP Strategy and Discussion
If you're looking to start a raiding guild, be sit semi hardcore, or full on hardcore, things are going to take time and alot of it, it's best to start any type of raiding guild with a group of friends / co-gamers who share the same ambitions as you, Starting a raiding guild solely by yourslef in most cases will end up being a recipe for disaster.
So, you have a few members, Now what?
Now it's time to start active recruitment, Try using your server guild recruitment channels, or even guild recruitment on your server forums, or use an un official guild recruitment site, there are a few out there, for example if you're a raiding guild, then try wowprogress.com
Tips on making your guild more proffesional
First and formost, get yourself a website, if you're worried about costs... don't be, you can use a site like GuildPortal Guild Website Hosting - World of Warcraft, EverQuest2, Lord of the Rings, Warhammer, more - Home which will allow you to create a personalized guild website absolutely free of charge.
Secondly, A voice server, whether it be teamspeak or ventrilo, this can be a great way to communicate with your guild members and keep them interested, it's always more fun when there are people to talk to.
Third and lastly, watch the members you recruit, try to make sure you recruit people who are sensible and do not make themselves stand out in a bad way, e.g Ninjaing loot in raids, that's never good for your guilds appearance.
Thank you very much for reading my basic guild establishment tips, if you have any questions or would like some advice please feel free to ask.