Personality is a big trait to look for no matter what vendor you are looking to hire for your wedding day, but when speaking to someone that will join you and your fiance together forever in front of all of your friends and family, you definitely want to be sure that you are comfortable with their personality. And vise versa, you want to make sure that he or she is comfortable with your personality and beliefs.
Some couples require a certain faith when looking for someone to perform the marriage. Some officiants are ministers, rabbis, or a justice of the peace. It is not likely that you will find a catholic priest to perform a marriage outside of a church, unless it is a family friend. But be sure when you are researching and interviewing that you discuss your faith with him or her so that they understand and are comfortable with any of the rituals that you would like to include in your ceremony.
When speaking with the officiants you are considering, be sure that they are well spoken and that they can carry a conversation with you comfortably. They should be able to speak clearly to you about your options without hesitation and should make you feel welcome. If they are going to be speaking in front of your guests, you want to make sure they are comfortable speaking with you.
Ask a Friend or Family Member
Many couples choose to go a different route when selecting someone to marry them. It is very popular for couples to find a very well spoken friend or family member get a one day marriage designation so that they can perform the service. If this is the way you choose to go, I recommend sitting down with this person and talking through the ceremony and what specifics you will want. I also recommend purchasing a book about wedding ceremonies to help you in writing the ceremony and personalizing it to you.
No matter what you decide, definitely do your research and ask your venues and other vendors for good recommendations. Also - be sure you do your research on how to obtain your marriage license as it can differ from town to town.