When I first start, I try and get all the auditions to build up some money - if you buy a computer for your room you can practice characterization and technique at night for free, which helps. Do the shady job at the mall to get an extra 10,000. I also build up my charm at night so I can get the modelling job (you can get it when your charm is alluring from the guy in the movie theater - you can get 6,000 twice a week, which basically pays your rent.)
I guess my main tip is focus on auditions first and making money, because as you gain fame the jobs pay more and more and then you can take more time to harass your chosen guy and buy him things on dates, which seems essential. I didn't miss any auditions throughout, and money became less and less of a concern.
Oh, and my secondary tip is to romance shuu first, because that gives you the cheat of max money for all the other playthroughs... but comes at the risk of wanting to romance him for all the other playthroughs, because he is *cute*. :D
Hope that helps!