The best positions for anal sex depend largely on what stage you and your partner are at in your experiences. Rear entry or the "doggie style" position is the one position most people associate with anal sex. However, rear entry allows a penis or anal toy to penetrate most deeply, and may not be the best choice for the beginner. A good starting position is the "spoons" position, with each partner laying on his or her side, one behind the other.
Of course using your hands for their genitals will leave you short-handed for keeping their cheeks spread, so this is where recruiting them to do either the spreading or the stimulation is pretty useful.