If you're struggling at the start:
Spend your memories getting the skills to boost the studies first. Most important is Bugs imo, get the second bug improvement asap. The reason for this is that studying with Rio gives a special effect: everything over 100 is converted into Memories and therefore more SP. Bugs also take up less resources, and at maximum, you can catch 6 a day for just 2 Action Points. Also, before studying with anyone, buy their item from the sweetshop and use, this gives you a buff to that activity for the rest of the day. After that, Bath skill is vital, as is a coax skill just to help top up your Lust. Sex skills can wait a while
Make sure before you do studying/sex, you use up all but one activity point. Grind gacha, buy soda, fish, play Menko, have a bath, look at some ass/tiddies, just make sure you don't waste time. The exception to this is mountain climbing, if you're doing that, go there first
Any doubles you get in the gacha can be given as gifts. It's a double benefit, you decrease Vigilance and you also increase Affection quickly. Additionally, give the porn mags to your uncle for a -20 Vigilance
Once you unlock it, make the Laptop part of your daily schedule, if not for its sidequest, but for the free stamina it gives if you say you're going to play outside