Similar background to yourself as an engineer, not in sales but as a co-founder often find the sales process a big part of my job.

We've implemented Strategic Selling see https://www.amazon.com.au/New-Strategic-Selling-Successful-C... which provides a great structure for us and a unified language inside our organisation.

Maybe not as useful if you're just trying to get started but does provide a structure to understand the sales process and why a sale closes or doesn't close.