Here, you can find a trainer for any specific field you want to practice in, or to learn a new jutsu, unless it's Kekkai Genkai. You can also spar with a trainer. (Another mod or I will NPC if you don't want to train yourself) They help you train significantly faster. Each one costs 30 points.

You can also buy scrolls which teach you a non Kekkai Genkai jutsu instantly, if it's at most, one above your rank. For example: Genin - C Chuunin - B Jounin - A
Scrolls cost a lot, though. Each costs 60 points.