Sexual misconduct is defined as:
Lama Tsongkhapa (and many others quoted) in his Great Treatise on the Stages of the Path to Enlightenment (eng v01 pg 220-221; tib 166-169) says:
Inappropriate people: Relatives, monastics, another's spouse, maidens protected by their parents, and those with whom it is illegal.
Inappropriate parts: Mouth, anus, calves, thighs, and the hand in motion.
Inappropriate places: Near holy places and people, near one's parents, in the presence of others, upon rough ground and so forth.
Inappropriate times: During the monthly period, near the end of pregnancy, while nursing, while a temporary vow of celibacy is held, when harmful due to illness, during the day, more than five times.
In short, guard your private parts and do not poison yourself with lust. Endeavor to form relationships, not just sexual partnerships. Never go against another's consent.