The game's idea is to play however you like, because eventually you'll get with the girls, so it's more about roleplaying a character in your head.
Now, if you want the game to go quick mafs, the shortest answer is "be a polite horny boi". Meaning, don't overstep yourself TOO much, always flirt with the girls and using the mostly safe option of rubbing their shoulders. Going to the swimming pool with them is also god. Meeting in the shower as well. Going for the addiction stuff will grant you easier access to them coochies, too. Jean Gray is a bit harder than the others, so you might want to leave her for last until you've caught on with shit, and Jubilee's got barely nothing, so you might as well forget about her.
Regarding money issues and leveling up, easy. Go to class, go to gym, study in your room in the night. If you do this, you'll build xp and since girls are by themselves, they'll earn xp on their own too. You'll earn passive income every day based on your level, and later on Xavier will tell you about microtransactions to get some more money. Once you have enough, you may want to buy the books and gift them to the girls. It's a one time only gift for each, but they grant 50 points on a stat (avoid giving them books that buff a stat they're already high, like the love book for Rogue, for example, it'd be kinda wasted money since her love stat is rarely gonna be insuficient to do things). Bikinis work good too. Not only for a visual reason, but because with bikinis, the girls can swim and can have "accidents" with their tops, which can be used to get more bonuses.
Well, that's the nickel tour, now you know where everything is... Anything more would be to straight up tossing a full save, but that's rarely fun.
