Well it depends on your interests. Photography is good. Pets, travel and food. If you have other hobbies you can write about them and share some photos of yourself.
To build up your account you can also comment on posts. But read the post and write a good comment not just "great post" lol

This is an old post of mine where I introduced some usefull steemit tools. You can check them out and choose whatever you find helpful.

https://steemit.com/steemit/@hanen/steem-tools-for-steemit-users-and-newbies