Use good formatting, good seo, good text, good media - either your own or give credit properly. All of these topics can be searched here for details of how to do them.

Post several times a week in your niche(s).
Make a schedule of your post topics and work on them in advance.
Search the hashtags for your niches a few times a week; read other people's post to get inspired. Notice the good and the bad.
Comment on other people's posts that are in your niche and follow them if you like their content.
Be sincere and post from the heart :)