Quoting myself from previously in this thread...
Very simply: Riley (handjob) and Aubrey (fingered) should always offer to help when you tell them about the list.
The condom can be taken from Ryan during the second free roam and the underwear can be found after Aubrey's scene.
Amber (bj) requires you to have told her to get clean.
Penelope (oral) requires you to have been on her path since CK1 and not have messed it up in CK2 (ie take her on the dinner date, don't let her get distracted by the other diners, next morning don't tell her you'd have preferred sex, save her from the conversation with Chris at the party).
Autumn (making out) requires you to not be dating Lauren, nor have broken up with her.
Lauren (sex) will, as you can't be, or have been, her BF, require you to have a loyal kct at the end of the party. Buy her the right present.