Right foot on rear brake and left foot on the ground.
Know your clutch friction point. As you release the clutch the bike will move forward at the friction point., Apply the throttle gently prior to the friction point,
Be mindful, you are on a hill now, whilst releasing the clutch increase the throttle in millimetres, a couple of seconds after, start releasing the rear brake (you will require a little more than you would on a flat road) listen to the engine. The bike may roll back slightly, this means not enough throttle, or you have released the rear brake too early. Pull the clutch, apply the rear brake and start the process again……. Relax