VX ACE SCRIPT REQUEST ~ PLEASE REPLY

For VX Ace I seen a tutorial for skill trees using simple events, well, I wanted to expand on that idea. When a character levels up, I want them to obtain an item (skill points, skill crystals or whatever) that lets them level up their skills, as I do not wish to have money deciding skills, because I want people to be limited to having so many skills by the time they fully level up (possibly only 1 or 2 skill trees fully completed) but I just don't know how to do that since I cant make scripts from nothing like quite a lot of people can.
So if anyone is reading this, please help me.