This is how I built my team. Not saying that it's the best way or the easiest but it shows that with a decent well thought out plan you can make it to the ABBL. While it is completely possible to build a team by purely training one type of player continually as players improve their skills their salary does not increase in a linear fashion so you'll get less bang for your buck. The sacrifice you make is that it is not likely that you'll have any NT players. But to win games you'll need 10 good players so building up depth through training is the goal. Basically if you don't train one type of player (or single position) for more than 2-3 seasons you'll never need to get anyone with a potential of higher than all-star until you can really afford it which saves you alot of cash.
Season 5-7.
Roster purge to only have 12 players. Minimise wages. Arena ticket prices @ 75-80% of max. Build more seats when full. Advanced level trainer? Advanced PR? (Not sure if was a long time ago, and a couple of staff skill level changes) Competent Doctor.
2 Position Guard Training
Train 5 guards in 2 position training (three were from the draft, investing 10k a week). The highest salary from this was 21k. It would be even lower if I hand focused more on driving and handling. I was new and didn't realise how important they were. Due to the supposed link between potential and salary (all-star potential training is meant to slow down training around 40-65k.) The potential of the players did not need to be high (there's a 6th man and starter in there) as guard salaries increase slower than big man salaries.
Sort of went AFK during season 7.
Sold 2 guard trainees to buy 3-4 C/PF trainees. 3 of the guards are still in my team (Starting SG, Backup SG, Backup SF).
Also bought Starting PF with proceeds.
Season 8-9
Exceptional level trainer hired.
Exceptional level PR hired.
2 Position C/PF Training
Bought Starting SF due to my teams relative low salary and the massive amount of money earned in the ABBL.
Train 5 C/PFs for 2 seasons. This is tricky due to the way big man salaries work. They balloon must faster than guard salaries so make sure you don't train them for too long. Also, potential becomes an issue much quicker. The highest salary from my training was 40k.
Sold 2 of C/PF trainees. 2 of the trainees are still in my team (Backup PF, Backup C).
Bought Starting C.
Season 10.
Single Position Guard Training
Bought 3 SG/PG 19yo trainees.
This training cycle will likely last for 4-5 seasons.
So yeah that's my 2 cents. Feel free to note anything that doesn't make sense or is incorrect.