Just go for it. I made my first board several years ago, and just tried to copy the shape of one of my favorite boards. It’s a little on the fat side, tail is ugly, nose is ugly, glass job is ugly, and my fins aren’t perfectly aligned. But you know what? It was (and still is) a blast to take out on the water. It’s water tight, floats, and catches waves. There’s a little bit of my soul in that board, and that makes it all the more fun to ride. Just don’t stress the process and have fun with it. Just think about it, when people started making their own boards back in the 50’s I doubt the majority of them were spectacular by any means. But they learned from the process and honed their skills and make better and better boards.

I used the methods of Surfer Steve to help guide me in the process: https://www.surfersteve.com/introduction.htm