Do not mix different brands of tattoo ink. Tattoo inks have very different bases. Some water, some plant extract, some alcohol. Only like bases should be mixed. The best way to make sure you dont mix bases is by buying the colors you need, or by only mixing same brand inks. Tattoo ink consists of a pigment and a carrier. The quality of the tattoo you create can only be as good as the ink you use, so dont under estimate the importance of quality tattoo ink.