Building on this, chose a player you want to train, and single position train him every week. Don't train a guard one week and then a big man the next. In this game, you need to decide what kind of team you want to be (Inside oriented or outside oriented) and train accordingly. At this level, train someone who is 18/19 and at least allstar potential. Once you have a trainee, focus on your stadium (as ToetotheFace has said) but you don't necessarily have to focus on staff, a level 4 (advanced) level trainer and level 3 (don't know what it is) PR should be fine. I still have a level one doctor in DIV and still do fine.
Also, OD is the most important skill in this game, so always put some extra pops there.
Good luck!