For a perfect and flawless make-up right mascara plays an huge role. To finish your eyes apply mascara in one light layer and comb through eye lashes with little comb. For a more daring or evening-out look apply the secong coat of mascara.
The right choice of mascara is also very important. You don't want to have you mascara to run down on your eyes, waterproof mascara is great choice, however, you don't want to apply mascara that would stick to your eyelashes for ever.
For everyday use Cover Girl Volume Exact is my favorite. It has a nice brush that separates eyelashes and doesn't create lumps on them. Also it is very light and you won't feel it at all. Even though it is not waterproof, it won't run down even in rain (it was tested by me).
For an evening look I prefer Maybelline Full Volume XXL. It has both conditioner and mascara. It's waterproof and it will define your eyes nicely. It is not hard to wash off with a bit of eye make-up remover.