The overall placement of the creep should be gradual, meaning that there should be an easy camp near the start location and as the player moves toward the contested parts of the map the camps should progressively get harder. The idea is to allow the player to do things in the early game, there should be options to rush, harass, or CC (Creep and Conquer)."
"Creep that guard goldmines should never be on camp mode because players will be able to fast expand or build towers near the camp without the creep attacking the constructing building."
(See whole article
here)