So, i'm 17, and 6,3. I am in shape, not fat or overweight, but i don't understand what to do next, I don't have access to a gym, and several people have recommended me Convict Conditioning and Starting Strength, I built myself a barbell and have been using water barrels filled with sand.

Every few days i do some situps, some pushups, deadlifts, squats and some cardio.

Am i doing something wrong? i wanna make sure i'm getting this right.