There are quite a few resources out there that can help you improve your technical writing skills. I will list some of my favorites here in the hopes that these resources will help other authors and technical editors.
The Writing Style Guide is available online and in a book format. It helps to ensure that you are using industry accepted language and is an excellent resource, regardless of whether you are writing a book on Microsoft products or some other technology.
Online Version: https://docs.microsoft.com/en-us/style-guide/welcome/
Book Version: Microsoft Manual of Style (4th Edition) (ISBN-13: 978-0735648715)
This organization offers webinars, classes, and digital and print versions of their journals. Regardless of whether you are just starting out with writing, or have been writing for a long time, you will find value with this org.
You can access their site here: https://www.stc.org/