lashes, here's a product that I've been using for years now. It's Dior's Diorshow Maximizer Lash Plumping Serum, which is technically a lash primer. It's got all sorts of nutrients to keep your lashes strong, plus it slightly thickens my thin lashes so I don't have to worry about using a really thick mascara that could potentially clump.
I've used other lash primers before but have seen the best results with this one. I just apply one coat to clean lashes (it goes on white) and follow with my mascara. I try not to let the primer completely dry hard because then the mascara doesn't go on as well.
Have you ever used a lash primer?