I think 100$ is very good to start. If is use .01 lot size then my daily target is 1$ to 2$. Then in one week i will get 5$ to 10$. If i use 0.1 lot size then my daily target is 2.5$ to 4$ then my weekly target is 12.5$ to 20$. I think is very save for my strategy. If you have very good strategy. Then you can use big lot size.