I have gotten questions about what I use to thin my paints with. Here it is! 1/4th of the Liquitex on the left, 1/4th on the W&N on the right and to top it off 2/4th of water. I use tap water but I've thought of trying to pick up some distilled water instead.
Is this the best thing ever? No, not really. But I like it:) I picked it up on the internet and it's suppose to be Jennifer Haley's old recipe. I might try out some other one in the future when I run out of these. In fact, I really recommend learning about the various tools that are out there.
Another version I've heard of is just using airbrush medium. Should work.
What I do then is to drop a few drops of the mix on a palette, get some of the paint, and mix it directly on the palette. I don't mix up a big blob but rather mix in a little of the mix into the color until it gets the right consistency. Figuring out what works for you and how to get a good mix that goes on smooth is an absolute must. Bad coverage and streaks is not a stylistic choice, it just looks bad :)