I don't understand the mechanics at all. First I tried studying at all costs but it wouldn't let me so I did random stuff like TV/Guitar. In the end he gets rid of all the stuff himself and I get a C+.
Then I replay and this time want to fail, so I make him refill booze and get drunk every day. Then after a couple of days he starts studying himself and gets an A+. When all i did was get drunk. Silly game.