lian_qiu has the right idea-except I don't use any tissue, it just gets in the way of things.
If you happen to smudge it on your skin, just wait for it to dry and wipe it off with a Q-Tip. It's also a good idea to gently comb thru them with an eyelash comb when they're dried, to prevent sticking. Under combing gently also helps prevent them from being too close to your undereye area-I know I get that problem, and my bottom lashes are pretty long.