Well, making specific suggestions is pretty hard, considering we don't have info on what kind of numbers, levels, and class makeup your raids will consist of. That's important in many ways - a larger raid can do more than a smaller raid, higher level raiders can do more than lower level, and so on.
Here are a few general suggestions, which you might be able to adapt for your raids. Raiding in its simpliest form breaks down to the following:
Tactics/Strategy - This makes or breaks raids more than any other single part of a raid. Knowing how to tackle a target usually is the difference between succeeding and failing. I note this first, since as a new raiding guild, this is where you are going to struggle the most.
Tanking - The better prepared your tank is (in terms of gear, levels, AA, and experience) the better chance you have at success. You will also need to utilize SA and offtank strategies depending on the fight, and teach your tank and raiders to use "Assist" and assist messages.
Healing - Keeping the tank alive to do their job is vital on raids. Depending on the target, there are a variety of healing solutions, but the most commonly used is a CHeal Rotation, where clerics take turns healing the tank. The difficulty of the target will determine the number of clerics and the frequency of the heal rotation. Teaching your clerics how to do a CH Rotation is vital in nearly every signficant raid.
Crowd Control/Splitting - Obviously, without being able to focus your raid's force on the target, and damage on the MT, you're going to have a hard time. Getting the target to the MT with the minimal number of adds, or controlling potential adds during the raid, is vital to success. Having your pull team and CC team prepared will help you a lot.
DPS - Of course, you'll need damage to actually kill the mob. Not too much to say here, other than more = better. Gearing your DPS classes will of course increase DPS, thus making raid targets die faster (thus reducing the load on your CHeal rotation mana pools).
Leadership/Communication - Lastly, having a leader who leads, makes decisions, and makes sure these decisions are followed out are a huge part of raiding. Making sure people communicate important information such as slows, debuffs, /disc status, adds, and assist messages will also help you be effective.
When beginning to raid, start slow and easy. It'll take a while for your guild to learn raid etiquite, so don't force extremely challenging raids on them while they learn. I would also recommend entertaining raids, and locations that are rarely visited. Lastly, making sure you have a CR plan, especially at first, would be recommended. No one wants to lose their corpse on their first raid.
Maybe with some more info we could offer a few early raid targets for you.