Tips to getting more followers-
Post lots, don’t go too long without posting something or your followers will lose interest.
Post interesting stuff, people don’t want to see pictures of your cat or what you are wearing that day, it just isn’t interesting.
Make posts that vary, like don’t always post pictures, and don’t always make text posts. That gets boring.
Advertise like you are on here.
Like and reblog people’s pictures so your name gets out there more.
Reply to people’s questions.
Ask people questions, like.. in their ask box. or just tell them you love their blog and stuff.
Tag your stuff, so when people search your posts come up.
And some people just follow back when you follow them.

What do people like on tumblr:

Harry Potter
memes.
Universe pictures.
Mean Girls quotes or pictures.
Mustaches.
Pictures of water.
Pokemon.
UNICORNS.
Wolves.
Quotes!!!
Anything funny.
Spongebob

Basically anything. But those are the main ones I can think of right now.

http://shelbybee.tumblr.com/
&
http://17teeth.tumblr.com I ALWAYS follow back instantly!