Step 1: Choose the Colors
NES Sprites can only use 3 colors from the palette or if you want you can use the "Megaman Trick" where you can use 6 colors, and how that works in the games is they Overlay 2 sprites over eachother.
Step 2: Start Spriting
I dont care how you do it just do it how you do it, and remember only the 3 colors you chose.
Step 3: Done!
You are done.