Lip primers fascinate me. I never though they would do much until I tried some, and now I am hooked! Most lip primers are essentially a thicker neutral colored base that fills in lip lines a bit and smooths things out for good lip color application. I find that they work well as a lipstick or high pigment gloss base, but they don’t tend to work well with lip liners. So here is a tip for you: line your lips before you apply the base and put the base inside of that line. Also, don’t use a lip primer with a lip stain or long wearing product. Those require clean and dry lips for proper application
One of the lip bases that I recently tried is Lumene Beauty Base. I picked it up at a CVS store, but ULTA Beauty also has also started carrying the Lumene line, which includes a number of neat skin care items. Lumene’s lip base is a tube with a sponge applicator. The base is like a thick matte gloss. Put it on, give it a minute to dry, and then apply your lip products as usual. The base makes them look smooth and the color lasts longer. Fun stuff!