Cover up designs require careful consideration when it comes to the kinds of shapes used; they must effectively break apart, conceal and integrate with the problematic area. It's a good idea to section off or chunk out the old tattoo into smaller areas and shapes instead of trying to just cover the whole thing in one go.
When you have a thick black armband like this, making huge wide shapes can create motion, fluidity, and direction in your design. For example, Jake used the blocky shape of this hammerhead shark to cut through the band at an angle which draws viewers' attention up into the waves before leading them down, past the old tattoo towards the other elements of the design.
You’re also going to need to make multiple passes at this stage, so packing in a layer of white into the thick dark areas at each pass can really help to break those shapes down even further. Now, you’ll never really be able to get rid of the black completely, this only lightens it about 15-20% every healed layer. This starts to neutralize the area and gives you some extra workability room to come in later with other shapes and colors.
Lastly for this section, the key to ensuring the new design stands out over the old one is contrast. Make sure the new design has darker features and hues compared to the original tattoo, as this will make a huge difference in separating both designs.