What you need: Vaseline and a clean mascara wand (a Q-tip also works)
What you do: Put a dab of Vaseline on your fingertip and dip the mascara wand in it until the brush is covered. (You can blot and smooth out any clumps with a damp piece of toilet paper.) Apply a light layer of Vaseline to your upper and lower lashes just like you would apply your mascara. (Be careful to avoid getting jelly in your eyes.)
Why this works: Vaseline mimics the effects of mascara, leaving you with lashes that look extra thick, shiny and voluminous. It will also help moisturize and strengthen said lashes (the opposite of mascara, which tends to dry them out).