Unlike the commercial platforms, there is no algorithm here pushing things into your feed (including trolls & bots). So what you see is 100% based on:
who you follow
what you RT
what hashtags you use and follow
(Yes, you can follow hashtags here!)
It's customary to post an #IntroductionToot using that hashtag. Tell a bit about yourself & your interests. (You can hashtag keywords for better visibility to other accounts.)
It can take a while to build a following, but your feed will be more positive than on other platforms, with NO ads.
Posts here are called "toots" (because the logo is a Mastodon)