Study this. Really, STUDY this.
https://www.boat-ed.com/newhampshire...uide/10103101/
Get a compass.
Get the folks renting the boat to you to spend as much time with you as you can possibly persuade them to going over operation, docking, checklist for what to do if the boat doesnt start, how to anchor.
If in doubt go slower...when the sh!t hits the fan its less messy at slower speeds.
If you dont know where you are...STOP...out of the way of boat traffic, and figure out where you are using map & compass and GPS.
Make sure your phone is fully charged.
Everyone on board wears PFDs, (lifejackets) ALL the time!
Be off the water well before dark.
Between Wolfeboro and Rattlesnake can be the roughest water on the lake if there is any real wind. A calm day can turn windy and wavy during a long lunch.
Kidnap an experienced Winni boater to help you out? Or bribe one. Seriously.