Struggling to understand districts

So I’ve been playing Timberborn on and off for a while now and I always reach a point where I get my initial settlement self sufficient and then struggle to figure out what to do next. I can’t really seem to wrap my head around what I need to do to expand to other areas of the map to get resources like metal and basically stall out each time. I’ve tried watching tutorials and walkthroughs on this game but I feel like they tend to jump through expansion without really explaining how they set it up. I tried to expand one time and had a mass die off because I didn’t have food where it needed to be. Does anybody have any advice on what to do past the early game?