A.M.
Congratulations on your wedding!!
One thing I assumed is that you don't wear make-up on a regular basis and "go bare"? Quite honestly, you might want to get a good foundation, some mascara and some lip-gloss and leave it at that. Rite Aid has a guarantee that if you buy make-up there and you don't like it, you can trade it for another shade. I'm not sure if other drug stores do that or not.
I've heard friends say that they have luck going to the cosmetic counter at the stores in the mall. Personally, I've never been able to get someone to help me out. But if you get someone, it's free, and they are supposed to be really good.
If you know someone who sells Mary Kay, you might be able to get them to help you out. Unless it's a good friend who is at your wedding, I would pay them for their trouble.
Cosmetic schools offer this service, but they don't train much, and I might use it as a last resort.
Check with your hair stylist. Are you having your hair done before the wedding? Ask if they can do your make-up, too.
Ask a bridesmaid to give you a lesson or help you out. There are a lot of websites that might be able to help you out, and you have plenty of time to practice. I did a quick search on Google and found this site: http://www.expertvillage.com/video-series/73_makeup-tips.htm which looks promising!
And last, but not least... Salon Visage offers an application for $30.
Good luck! I"m sure everything will be great!
A.