The most important quality for the designer is to have artistic taste. Try to objectively figure it out if you have it. Do you regularly get complimented on your clothing choices? Do you always match colors? Does your apartment look cool (if you did your own decoration)? If you're not sure, ask some non-family members for their objective opinion.

If you find out that you don't have much artistic taste, don't worry - most geeks don't. That just means you have to hire a designer, because yes, a good design is VERY important.