There are a lot of ways to increase the number of likes of your photos. First, is to increase your following (in Facebook's case, increase your network or add new people), the more people you have, the more chances that you will get more likes. Second, post good quality photos. People will like photos if it's good quality. Third, write a better caption, something that will catch people's attention. Fourth, #likeforlike, if you like other people's photo, chances are they will return the favor. Fifth, make friends with them, you can have a chitchat or comment on their photos. Sixth, autolikers, but I dont really consider this because this is a desperate thing to do.