I have naturally long eyelashes, but I use Stiletto mascara, I put it on, wait 30 seconds, and re apply, until they look the way you want them to. Also if you have a clumping problem, before you apply it, wipe it across the top of the bottle, because it helps prevent clumping, I always do this, I learned it from a friend, and have not had a problem since.
There is no such thing as flawless, but mascara helps make them longer, and an eyelash curler can make them look flawless. You have to make sure you buy the right brand of mascara though because a lot of them make your eyelashes clump together
Get and old mascara bottle or one that your not using any more and take the brush and clean it. Once it's clean take a small amount of or extra virgin olive oil and put it on the mascara brush. Make sure you don't have any eye makeup on then apply it like regular mascara that helps for me hope I helps you :)