Ideas for making a positve/negative chart for a four year old?

i have charts for my kids. they have 100squares. every time they help me out, do things i ask, and follow the rules i give them a sticker. so that's the positive. when they don't follow rules and refuse to do Something i ask i take a sticker away, that would be the negative. at most i give 4 stickers a day. when they fill it they get a prize... a new bike. maybe just starting with your child try less squares and simple prizes.