Look at the designer’s site.
Look at the sites from her/his portfolio.
If you like her work, go ahead and contact her. If you don’t, continue your search.

After you’ve found a designer whose style appeals to you, tell her what you want and ask her to explain to you, in detail and in layman’s terms, what you will get.
If you do not understand, ask again.
Don’t be afraid to ask, but be afraid rather, to hire a designer who is unable to explain to you what she’ll be doing and exactly what you’ll be getting in the end.

Some of the points which must be clarified at the outset:
• who will provide images and graphics for the site?
• what happens if you want to introduce some changes after initial agreements?
• which browsers will your site be tested for?
• who will be putting your site on the server?
• how will subsequent maintenance, upgrading and changes to your site be handled?