You should make a table with modifications of the Attributes. This values can change during the life of a charakter. The range for a human is 1 to 10. All values are absolute, not relative to a race. Skills Skills are all the things a Charakter learns during his life.
Every skill belongs to a attribute.
The value of the skill can't grow over the value of the atribute. The Equipment of the Chakter must be clearly noted somewhere. Especially where the item is stored is importend. Free ED are distributed after solved tasks or adventures, linked ED after using special skills very often. When the Player has chosen a skill he throws a open D10.