Just make sure you're buying the first position, not any other junior positions. I've heard newbies doing court auction purchases only to find out the trustee sale was for the 2nd lien. Not fun if the 1st will foreclose on you once you take that position.
If you do buy the first position, then you'll need to get ready for some legal action to evict the occupants. Get with a lawyer for that...
If you don't want to do trustee sale buying, then wait for the lender of the first to bring it to market with an REO agent. Depending on the condition of the property, the listing price will be priced lower than FMV for quick sale. If it's down right a dump, you may get a good price for the dump...get ready for fixing up and maybe get it up to code.
Lots to think about. I guess my question to you is, why do you want to buy a house, especially a foreclosed house?