In order to set up a tattoo cover-up, I first like to prep my workstation. Materials I have with me at all times when doing a tattoo- cover application are: astringent to clean the skin, cotton pads, shavers (electric and razor), shaving cream, scissors, adhesive (Pros-Aide), latex sponges, tissue, spray bottle (water), No-Color powder, powder puffs, Q-tips, 99 percent alcohol, brushes, sealer (Ben Nye’s Final Seal), hand towels, Isopropyl Myristate, Supersolv lotion (body, hand, or face), Anti Shine, Mac Creme Gloss Brilliance, tattoo palettes in flesh tones and primary colors; I use Skin Illustrator, Reel Color, W. M CREATIONS, airbrush tattoo colors from Skin Illustrator, Derma Palettes,
airbrush and compressor (all items are Industry Standards).
No matter what approach you will take for tattoo cover-up application, you will commonly prep the skin by cleansing it with an astringent of your choice. Doing so removes dirt and oil, and slightly dries the skin for better adhesion of makeup and paint.
Depending on the size of the tattoo you are covering, you may choose to airbrush or paint it out using your makeup brushes. Either way, the colors you choose to use should remain the same. I like to think of this as though you were painting an opaque prosthetic (foam). The idea is to have a color that is not conducive to looking real, and it’s attached to the skin. Your job is to make it imitate clean skin, and to blend by painting. When I say paint, I mean paint as though you have a blank canvas.
1. First, you need to start by blocking out all color of the tattoo. I like to go with a meaty red-orange color first. Paint the color solid over the whole tattoo, right to the edge, and then blend and feather it out only about a 1/2 inch from the edge. This not only helps block out the blues and blacks used in most tattoos, but also gives you an undertone to your flesh colors.
2. Next, go in with a natural flesh tone that is about one shade lighter than the actor’s own skin tone. Stipple this color over the surface—making sure it has solid coverage, but with variations of transparency.
3. 
Add yellows, blues, or greens to the skin to adjust the color by graying, cooling,
or warming the painted area. This should give you the overall match you are looking for.
Details:
Lightly apply a hotter red to the surface already painted to bring out the effects of capillaries and natural blush colors found in the skin tones. Freckles and the occasional browning of the skin can tie the look all together.
Adjust the shade of your tattoo cover-up as you wrap around the body. Not every angle of the body has the same degree of warmth. When working on darker skin tones, you will be using reds and sometimes yellows.
4. After you are done covering up the tattoo, a thin spray of sealer over the surface will help protect it. If your image is a little too shiny, add a little antishine over the surface. Try to avoid powders. Flesh-tone tattoo paints, lightly applied over the surface, can help. Use silicone or water-based product.
Note: Never put oils such as glycerin on top of your tattoo cover for a wet or sweaty look. This will break down the cover.
For on-set touch-ups, always have your paints and makeup colors with you in case you have to remove and reapply on set. For minor repairs, have premixed colors to match and fill in areas that have rubbed away.
For removal of tattoo cover, mix Isoproply Myristate and SuperSolv in a 50/50 solution.
Warm the mixture to a temperature comfortable to the skin. Gently rub the
remover with a powder puff in a circular motion on the area to be cleaned. Follow with a dampened hot hand towel to remove all solvent.