Two products that I've started using in the past year are eyelash primer, and face primer. They both make a HUGE difference in how your products go on and stay put, and I can't live without them now! They are not just a gimmick and one more product to buy...they truly were created for a reason!!
The lash primer thickens your lashes so that when you put on your mascara, your lashes look fuller and longer! The face primer minimizes your pores and makes your primer go on smoother and creates a more flawless finish! (If you haven't seen the orange analogy with and without primer, look it up and you'll be amazed by the difference!!)
My favorite for lashes: Mary Kay lash primer, followed by lash love of course!!!
Face primer: Younique glorious face primer