you can post any kind of content on steemit, but if you are looking to get some post rewards then you will have to make sure that your content is quality content and not copied content. you have to choose a topic you like and you can write consistently, your topic should have a community also which will follow you over a period of time.
the most important thing is to be consistent and make sure you can do the grind. there is no quick way to get alot of post rewards on steem without investment you will have to bite your time, spend alot of hours, work it out and make sure you write regularly.
after a few months you will get around it and things will become easy.
