I have found that when adding cocoa to a beer, you want to make a paste like Oldstock says, though if you use an alcohol (I use creme de cacao for even more chocolate), the cocoa goes into solution more readily compared to water where it tends to be in suspension.
Primary 1:NE IPA Style Saison
Primary 2: Raspberry Wheat
Primary 3: Typical Pale Ale
Up next: Lemon and Thyme Blonde