Follow
Gaining a lot of followers should be your ultimate goal. Those are the people who enjoy your content and want more of it. They will engage with your content regularly, e.g. by liking your new posts and, thereby, helping you to get even more followers.
How to get followers? The best answer is: by following others! Many people will follow you back, however, only if they are interested in your niche.
The way most people and most bots follow is that they simply follow other people who publish content. For example, you type in ?milf? into the Tumblr search and then follow all milf blogs.
I think that this way of following is actually really, really bad. The reason is that if you just follow everyone on the results page, you won?t get to your actual target audience. Most of those blogs have commercial interests themselves, as they are ran by other adult webmasters. They won?t follow you and they won?t click on your links or buy anything from you.
It?s like you being a bookseller and then going to another bookseller trying to sell him your books. Can work, will work sometimes, but selling to actual consumers will be way more successful.
The right way to do it, therefore, is to follow people that engage with content within your niche. Let?s take the MILF niche example again: I type MILF into the search box and check the results page.
Now, I sort the results by ?most popular? and ?photo?. This will only show the most popular pics (= pics with most social interactions).
Click on ?Notes? to check who engaged with the content. Now, you will see a long list of people who engaged with this particular post. Follow them!