My advice to new managers is always - don't spend a lot of money early
If you intend to play the game for any length of time, the arena is the most important investment you can make. And it will take several seasons to completely build it out (20550 capacity)
I wouldn't worry about the draft.Unless you intend to field a fully home grown team, it's usually a waste of money
After the draft, there is what I call the "back draft". After the new season starts, there will be a bunch of 18 year old players on the TL. You can draft serviceable players for less than 10000. And it's better to learn how training works with cheap players rather than expensive ones
Concentrate on PAS or SS players to start with. You can't afford a fully developed MVP or HOF player early on. Better to have 5 players earning 20k than one player earning 100k
Decide if you want to train guards or big men. Try to find players with similar stats so you can focus on training a few key stats. Avoid players with low stamina