I definitely second learning how to draw realistic eyes first.
That's a must pretty much if you want to draw really good anime anything.
Aside from that, just practice eyes all the time.
And try to remember to use guidelines, just take out a ruler and draw two straight lines based on how bigs you want the eyes to be, and keep your eyes between the guidelines, this way your eyes should be even in size (and after getting them even in size, just drawing in the pupils and highlights should be pretty easy).
And yeah, if you do all of that, your eyes should look great! ^-^