Well, you have to use those that are applicable. If you try to use ones that may be more popular but that don't apply, you could get flagged. I would try searching for "most popular tags" and see what you find, and then maybe use any that apply. I would think if you are doing photo journals tags like "life," "nature," "travel," "photography" would come into play a lot. One I use all the time for photos is #ucd-resteem, because those are actual members that pay for good photography, and they may resteem your content, as well.

Good luck!