I presume you are referring to an REO property which has already gone through foreclosure. If this is the case, then they are very easy to buy as long as you have the right funds. Some are very distressed and are cash only and some will allow financing but only conventional financing (not FHA) based on condition. Depending on who owns the home (HUD, VA, Chase, Bank of America, Etc...) they have different sets of addendums, contracts, timelines, etc.
A local agent should be able to guide you. If you are refereeing to a property undergoing foreclosure, then that is more complicated. If the home is a short sale, you would actually be negotiating with bot the owners and the bank and both would have to agree to your offer. Short sales can be frustrating and can take months before you know if you can close or if the deal falls apart.