Ensure that there is adequate frontal coverage to absorb urine, and also check to make sure that the whole liner is really inside the diaper cover so that moisture cannot wick from the inside of the diaper to the outside.
If you're not going for the full-on smoky, completely dark eye, you can even choose a white or light peach liner to apply to the lower water line to give the illusion of opening the eyes back up (dark colors tend to make eyes look smaller).
Single or Multi: While cotton and other materials are often waterproof, water repellant, or water resistant, many people opt for a fashionable curtain made of designer fabrics combined with a plastic or waterproofed inner curtain liner.
The fresh-faced appeal of understated eye makeup is one that can easily be pulled off for every day with a flesh colored eye shadow, a brown or other medium neutral liner on the top eye, and two coast of mascara on curled lashes.
Note that 'pull-up' covers (the kind traditionally used with cloth diapers before there were disposables) can be slightly more difficult in terms of aligning the liner with the cover, but a little practice is all it takes.