When you first start and have 5k equipment its honestly nearly impossible to past Tier-4. Once you get 50k equipment you'll be able to train guys better and get them into higher orgs easier.
The main thing you need to do is try to do is pick a style and train only the stats for that style. Once you pick a style, designate fighters to be your trainers. And train 1 stat with that guy as much as you can, try to get it as high as you can. Then he can teach other guys that stat. Hope this helps.
The Bus Riders