Also, a lot a lot of people have troubles when it comes to first wearing contacts. Naturally, you're not supposted to stick things on your eye, so your body naturally tries to stop you.
A lot of doctors (for a fee) will help you put in your first pair of contacts, and then teach you how to do it yourself. It took me almost a full week to get used to putting in contacts, and it takes others even longer. You don't want to try to put in coloured contacts right off the bat, especially if you've never worn them before. You'll probably end up not even being able to get them in, losing them, or even damaging them because you're trying to put them in wrong.