MC in my game is far from having much charm even now (he's barely approaching 40 and was at just 30 until not too long ago) but it's quite enough to pass basic checks more often than not. Do basic upgrades to rooms so they don't penalize you, make sure your MC isn't dirty/filthy, read some books on charm/manipulation to increase them, try seduction->caress for crit success increases. Use simple affection raising actions (diner, asking if the girl is ok, etc) to raise affection levels, which will increase your chances down the road. If you can get girl's arousal during seduction to more than 10 you stand a good chance to convince her to have sex, and with this amount of arousal it's almost guaranteed orgasm for her, which will increase affection for subsequent attempts.How do you guys deal with the early game when you can't charm or manipulate anything? How do you deal with slaves?
Can't request sex, can't compliment, can't encourage, can't affect, can't explain. Any interaction basically will 99.9% fail, might as well not try. Do you savescum or just avoid talking to them until much, much later when you have better skills?
Some of the girls you can pick up early start with some affection towards MC already, which also makes things easier.