Hashtags are convenient and can help your photos get featured and attract more followers, but only if said hashtags are relevant. Have a look around Instagram, check out your favourite profiles and see what hashtags they use. There’s a lot of different communities on Instagram and they all have their hashtags. Find the ones you like and that are similar to what you post and use those. And please, for the love of god, don’t fall for that #followback bullsh*t.