Eyes study

I find that just a dark line, not even a very thick line, is enough for eyelash impression.

I quite like the way Adam Hughes does it. Look him up.

It looks like the artist who did the IFX cover drew the eyelashes as you were describing, Sapirlapid, and drew a thicker black shape over the eyelid to suggest the base of the lashes and then drew in individual lashes on top of it.

As for drawing individual lashes, I think part of your problem is that you seem to be making each lash fairly thick and separate from the lashes around it. Lashes taper very quickly and are extremely thin at the ends. Furthermore, lashes grow in groups and tend to clump and cross over each other to form little triangle shapes that are typically more sparse-looking than how you are drawing them.

I would totally suggest looking at and observing your own eyes! Another (odd) suggestion I have is to look at makeup videos on youtube. The makeup artists (especially KlairedelysArt) generally spend a long time with the camera focused on their eye(s), so you get a chance to look at a nice closeup of an eye and see how people use makeup to change its appearance through things like eyeshadow, eyeliner, mascara, and false lashes.