There are several ways that maintaining a logbook will improve your observing and imaging skills. For one, it will force you to organize your observing and imaging sessions to get the most out of a good clear night, especially if you have to travel a fair distance to get to good Bortle 3 or better dark skies. You don’t want to necessarily do a Messier marathon, but if you want to try to observe or image the most interesting objects that will be available, you’ll need to be organized.
When planning your imaging sessions, you’ll want to understand and record beforehand the specific details of the objects you’re targeting so you’ll know the kinds of detailed characteristics of the object you plan to image and have as a guide to set your equipment up for the task. You’ll want to record information such as the equipment settings you’re using, the seeing and transparency conditions of the night and the focus settings for any filters you use or if you don’t. You’ll want to include details on any problems you encountered during the session and the solutions you discovered. Accurately recording this kind of information and reviewing it afterwards can be very effective in being able to evaluate your equipment and your skills to understand where you need to improve before your next imaging session. Having a detailed record of your adventures in imaging also provides an opportunity to have fun when you use it to review your progression from a wide eyed beginner to a seasoned veteran.
The most popular logbook I’ve seen is from Blue Planet Photography - this is the Astrophotographer’s Logbook. This is the one I use and it’s geared exclusively for astrophotography. I have all of my equipment and camera settings and specs referenced in this book so I don’t have to go searching my memory for them when I need them. Recording information is pretty straightforward. You can get a copy via the link here: https://blueplanetphoto.com/product/the-astrophotographers-log-book-25-sessions/?v=7516fd43adaa