Color magic 
TKB's Presto Change-o Magic Color Lip Liquid is a color additive.  You don't put it on your lips directly, you add it to your project.  And frankly, you don't need to add much.  We used to recommend between 2%-5% by weight, but customer reviews have advised to take that number down.  Maybe 0.5% to start.  For our Halloween Kit colors, we did end up around 3%.  But you should "work your way up".

All this means that a 1 fluid ounce bottle of TKB Magic Presto Change-o Magic Color Lip Liquid will easily color 1-2 pounds of base.  (Note: you could put it directly on your lips but your lips would be stained extremely pink and you would regret it.  Save that idea for when you want to get back at your pesky little brother and be grounded for a week).
By the way, the best way to remove it from the skin is with a makeup remover or an oil.  That is more gentle than scrubbing at it with soap and water.
How to work with it:
Add it to a lip balm, lip stick, lip gloss, and -- possibly -- a lip oil.  If you add to a lip oil, the oil must be thick enough to keep the color "suspended". If it is too thin, the color will settle out.  Daring folk can add to a cheek stain or use for a similar purpose.
More is not always better, so start with the least amount possible and increase as you need.  Here is an image showing what the product looks like added to clear Lip Gloss Base.  You can see that adding the color will impact the color of the product in the bottle.