1. Quality Content above all. If it's good quality a lot of people will link to your website, share its contents, and eventually increase DA.
2. Do on-page optimization and internal links to your photos and pages. Also much better if the pages load fast.
3. Do Forum Posting and Blog comment from sites with high DA. But don't overdo it cause it will be tagged as spam.
4. Avoid keyword stuffing and comment spamming of your links.
5. Observe good SEO practices. Use effective keyword tools, find the best keywords, and utilize them to your advantage.
6. You can also be a guest blogger for other sites to help them increase traffic and grow. After some time, they will also come to your site and do the same.
7. In relation to tip 6, you can also have someone who can do guest blogging for you. It's a win-win for both parties.