When Will You Wear Them?
Fashion lenses are most popular with people who want to use them on a regular basis, unlike costume lenses, which are often worn only for a day or two at a time. You might want to wear your fashion colored contacts every day. They might be something you wear only on weekends or outside your day to day routine.
It all depends on how you'd like to present yourself. For infrequent use or to try the lenses out, you might want to buy single-day contacts or lenses rated for a month at a time. If you know you want to change your eye color long-term, look for coloured contacts rated to last three months to a year. These lenses will withstand cleaning better and provide greater comfort.

How Many Should You Buy?
Most people will need more than just one pair of contact lenses. After all, even one-month contact require occasional cleaning. Purchase two or three pairs at a time to ensure that you can wear one while giving the other the proper treatment. It'll help keep your contact lenses in good condition longer and you'll feel more comfortable wearing them. You can even switch between two or more colors to give your self an ever-changing new look!