If you have a really steady hand then masking won't be necessary.When the paint dries completely, peel off the tapes but be very careful so that the colour beneath the tapes are not disturbed. Now paint black along the taped portion first and then move on to the rest. Right Side: Now mark the midsection again (this time use pencil as little as possible) and add masking tapes along the line covering the orange side. Left side: When all the markings are done, start with the lighter colour which in this case is orange. There are many eye designs of Deathstroke's mask so go for the one you like most. Although you may need to do this later again, it gives a much better idea of what to do. When the primer feels even after 1 or 2 coats, get a pencil and mark the eye and the midsection. If the white colouring still shows anything from underneath, coat again. To get even colouring, first paint it white as primer and let it dry.