Hashtags are also a good place to start! For example, if you're looking for science content you can follow the #science hashtag. Once you have those posts coming in to your feed, start following the people and hashtags you're seeing on the posts you like best. It'll start snowballing from there.
Also, don't worry too much about following too much at first. Get that feed populated, then pare it down later. Filtering is pretty powerful too, so a lot of times you can get the good parts of a hashtag and filter out the bad parts instead of the all-or-nothing following of some social media.
Agreed! Especially since the behavior on clicking a thumbnail isn't very consistent on mobile. Sometimes I click the thumbnail and it expands the image. Sometimes it follows a link. Sometimes going back from a link takes me back to the same Lemmy page I was on, but other times it reloads the page and I can't find the post I was looking at anymore. An option to open all links in a new tab would really help me not lose the post I was looking at when I clicked.