The first part of any successful marketing campaign is to create an attractive, inviting gallery. I personally like ones that have benches where you can sit to look at the art. Make sure that no lights are glaring in your eyes from anywhere you sit or stand.
Second, you want to have a guest book so that you can contact your visitors again and again. A small number will buy on impulse, but more will buy on a second, third or fourth visit. You need to remind them that you are still in business, and of any new shows or prints you have.
Third, it is important to brush and floss your teeth, and rinse with hydrogen peroxide. You would be surprised how many gallery owners have bad breath! Dress and groom your hair to be like your visitors. Avoid tatoos, earrings for men, and weird hair colors or styles. Keep your art on the walls and off your body.
Fourth, greet your visitors with warmth, ask them where they are from, and what they like in art. In other words, be nice. Too many gallery owners treat their visitors with disdain. Always give them a gift (postcard is fine) that has your contact information on it so that they can get back to you.
If someone complains about something in your gallery or art, thank them, and tell them how much you appreciate their comments. If they compliment your work, thank them also.
If you use any special or unusual equipment, you may want to create an area in your gallery with photos that explain how you use it. A short biography is also helpful, as many will want to know how you got into photography.
All of this is the core of marketing. It is what creates good word of mouth advertising. People who like you and your work may not buy, but they will talk positively about you to others who will.
Next, you need to find out who buys art in your town. Is it permanent residents, winter residents, or tourists. Other gallery owners will help you with this. Then you need to find out how to let these people know about you. Direct mail is good. You may be able to get lists of winter residents and send them a postcard with your best image, an announcement of your opening, and a time-limited X% off for their first purchase. Other store owners may let you display a stack of postcards in their store.
Get the local paper to do a story on your opening, and then get permission to reprint the story. It will make a nice handout to your visitors.
Everyone needs healthcare, so see if the local doctors would be interested in hanging your work in their office with a small card showing the location of your gallery. You may have to offer them a discount. Local restaurants may also hang your work on their walls.
Hope this helps.