There are a couple of things to watch out for. New teams get $50,000 per week for the first few weeks. You might think your finances are in better shape than they are.
In addition, the 3 TV games pay out a lot - you will get TV money for your game on Saturday, even though you are the visiting team. Last season, I typically lost money in most weeks and made it up with the TV games.
I don't think I would upgrade to a top level coach immediately. The money might be better spent on getting some better players. You might also want to consider a better doctor - or you can wait until you have an injury. With a "1 level" doctor, injuries don't seem to heal very quickly. With a "6 level" doctor, an injury to a player who is 23 to 24 seems to heal about as quickly as the original estimate.
The staff hiring is kind of odd in BB. 3 specialists are offered each week (starting on Monday, I think). So some weeks you might be offered a "1 level" doctor and "4 level" trainer. So you could hire a "10 level" trainer, and then decide you can't afford him. But you check who you can hire, and it is another "10" or perhaps a "1". You also have to pay the salary of staff member who is fired for one week. So a "10" at this time might be a little too expensive. If you can hire the "6" it's not going to put you at too high risk.