Stranded wire, 20-22AWG. Buy extra, measure many cut once. I use Velcro tape and staples to attach to my cab. As well as small black zip ties for when I make prebuilt wire snakes. I also try to avoid those little sticky zip tie pylons. Take your time, use proper tools, and the wire might need to be worked a little when it comes off the spool.
I buy my stuff local from MRO Electronics here in Calgary. If you can't find local you could try eBay or Amazon.