Notes from my first tour, when I didn't know anything:
take your time
the last bit is the hard part
get directions right, while getting lost can be fun, you'll be annoyed at wasting energy backtracking
put your phone on airplane mode while you ride and know where you are going. It saves battery.
I find waving to other bikers makes it feel more communal if you are riding alone.
wear gloves or put sunscreen on your hands... Or... Rip holes in the extra pair of socks you brought and use those.
bring more water.
bring good snacks.
know how your panniers are organized
bring lipchap, moisturizer, sanitizer.
I still don't know much.