HI Pete
I agree with Colin.
A good solid building board is also essential. 3/4" MDF is my preferred choice. Mark a centre line down the length of the board. Depending on how you are building the hull make sure your keel follows the line or frames are equally spaced about thew line. I would tack glue blocks of wood to the keel or frames to keep everything straight and square.

A dry run will show up any problems which you must resolve before starting to glue. I usually use cyano to tack in place initially.

Take your time and check, check and check again.

Before you skin the hull you may want to fit the propshaft and motor as alignment will be so much easier.

Good luck with the build 😀

HI Pete,
if you read through build instructions twice first, then try a dry build without glue to check fit.When you are happy that you can start assembly without interruption take your time as the first frame assembly is what determines the finished shape. (You'll make mistakes but that teaches you.)
As for coatings/paints etc. that's a matter of personal choice, I try to use good quality marine paint, (but that's my choice).
water proofing the interior, again personal choice, I use either a thin epoxy resin or polyester resin.
Don't forget to ask for help when you aren't sure. Many of the model builders on this site have helped me in the past and as you are building one of the classics I'm sure you'll get loads of help. Try reading a couple of build blogs, especially RIVARAMA.
Best of luck Colin.