I agree with what jimrtex says….so I won’t repeat the advice he gives, but rather add to that.
SG, SF training in JS, JR, OD, PA, DR, HA
PF training in JS, IS, ID, RE, SB
C training in IS, IS, RE, SB
If you train 1 position you can train 3 players per week (if you have 3 games)
So I would start out by training JS as you can then train your SG, SF and PF.
After a couple of skill ups (max. up to Proficient) I would buy a Point Guard Trainee and train him instead of the Power Forward. Then I would train the other outside skills JR, OD, PA, DR, HA and maybe buy an additional 3 trainees (total of 6) and train 2 spots (PG and SG).
Don’t train any skill too high in the beginning as your wages will be too high (Respectable/Proficient is max), unless you want to sell the player, where you could take the player 1-2 levels higher. (Respectable is a bit low if you want to sell for a good price)
I like my players quite even in the relevant skills if I want to keep him as this is better for performance (IMO), and bump the skills - especially shooting - if you want to sell him. Prices seems to go much higher for good shooters for some reason.
And remember to train OD – good defence is very important for your team performance (you will meet many team that train shooting)
Also….be careful not to spend too much money on players in the beginning. I you train Outside Players just upgrade you Inside Positiions (C, PF) with nice well rounded players. Decent Inside players are very cheap. Just check the Center I have for sale - U don’t have to buy him - I cannot sell him, even if he would contribute nicely to most new teams. And remember age does not matter on non-trainee positions.