Yesterday I ran Ethernet (through an underground conduit and some walls), crimped it, and installed jacks all for the first time.

Networking feels just a little faster when you hand arranged each little wire.

Any lessons learned from doing it? Been thinking about replacing coax and phone cables but haven't had the time or urgency to do it!

You might be able to use existing coax! Look into “moca” adapters. 

In my very limited experience, the “tool free” keystone connectors worked fine. And for the rj45 you can get pretty cheap sets with a crimper/cutter, pass-through connectors, and a line tester.

I didn’t do any complex fishing through walls. Not sure how that works!