A very common mistake is to commute what you'd drive. In many cases you'd do better on paths and neighborhood streets. For example, maybe part of an unavoidable highway segment has a frontage road. Hop off onto the frontage for that segment, even if it's technically 60 seconds slower.
Google Maps is a decent start, though imperfect in detail (routing through a busy park on footpaths, or not routing through a park that has a good dirt path). Use street view and OpenStreetMaps to explore ways that auto routing won't pick.
+1 to the suggestions on starting with shorter trips. They'll work out any kinks in your setup and give you time to become confident on your bike.
I own a Tern Verge D9. It's a functional and sporty folder.
The Verge is a snappy feeling ride. Think road-bike handing. The tires are also good, but at 30mm it won't like anything rougher than hard-pack dirt. They're also ISO 451, not the more common 406. This size has fewer tires to choose from for a slightly nicer roll. It's up to you to not if that's a worthy hassle.
FYI, the magnetic latch is terrible. You will have chipped paint on the fork. I don't mind but you may.
Careful folding and unfolding. The stem fold likes to bite the brake and shifting lines. That will screw up shifting.
The matching rack they sell uses oversized tubes. You may need to replace the hooks on existing panniers. Also the racks sits closely to the pedals, so large things may have some foot overlap.
I'm sure I have other thoughts floating around about the Verge D9. Ask anything you'd like to know about it and I'll try answering.