Buy a book -
http://www.amazon.com/Planting-Food-Plots-Other-Wildlife/dp/0970749341
My advice for people that are starting out is to contact the real seed companies that has developed products specifically ment for deer, and they will send you their catalog's. Not some local feed and seed store that is selling something ment for cows and horses.
Mossy Oak Biologic -
http://www.mossyoakbiologic.com/
WhiteTail Institute -
http://www.whitetailinstitute.com/products/extreme/
Tecomate -
http://www.aboutus.org/TecoMate.com