Budget. Decide on your budget. It will help you to narrow down your search.
Style. Know what kind of photography style you like (photojournalism , classic portraits , fine art, etc.) and look for the best match. You don't want to be surpised receiving all black and white images.
Portfolio. Check photographer’s portfolio. Make sure to take a look on full wedding stories.
Experience. An experienced photographer is more secure option than a new freelancer. You won’t have a second chance to capture your wedding day. Even though a freelancer could be easier on your budget.
Location. If you know your ceremony and the reception location, it would help a photographer to be technically prepared in advance. Depending on a distance, it could influence the package price too.