It's hard to tell you how much money and progression points you need for training a skill/stat.
Each skill and stat requires a different amount of progression points to train it.
And with skills it's even more difficult to train, because each higher level will require more progression points and more money.
When you open you're skills and stats box, you see a yellow and red bar behind every skill/stat.
the first yellow bar, shows you the amount of training you need to do, before you can start it practicing
You need to fill the yellow bar till it's fully green and can't train higher anymore.
From that point you need to practice the skill till the red bar is fully green too and then you are done with that level.
Each progression point, that you are using will also cost you 42 trias.
Also if you look more close at the same bar, you also see a small blue bar.
This blue bar shows you how much progression points you have and how much you can train, compared to the required amount of training.