Alright boys, I've been converted to the light side and have installed F-Droid. Now what?

Basically title. I waited on installing F droid for a long time because my phone threw many scary warnings when I tried a long time ago. But now I have it, and I got some fossify apps, but since there is no "Editor's Picks" on F- droid I dont really know where to go from here.

What apps do you recommend I install first to remove my dependence on closed ecosystems?

What is my vulnerability surface ie, which sort of apps should I watch out for?

Are there any bad faith companies in the open source sphere?