When I started building, I found that the most important was to follow other Builders and look at the projects they've done and their style. Develop a style that suits you and your way of building. Look for feedback from other builders to help improve and change your style and way of thinking when it comes to attacking a new build. Once you get used to building in your style it'll become so natural that you won't even have to think twice.

I suggest finding a builder or team that you like, and sort of attempting to copy their style. This can help teach you about patterns and how to build nice looking structures. Once you've tried to building in their style for a while(basically until you feel comfortable) try just building your own thing. I think you'll find that while you do take in and use a bunch of their styles, you'll have modified them to the way you like, or a way that's easier for you and it'll have become your own style. As you keep building it'll gradually drift away from where you started and eventually you won't even be able to tell you got inspiration from someone. At least that's how it worked for me. I found a builder I liked, sort of copied his stuff for a bit and then branched out and started doing my own thing.

If you'd be interested then we have a so called "Learner" rank on GreenLeaf Creative :p
It basiclly gives you acces to all World Edit and Voxel Sniper tools, and you'll get help with your creations from out Build-judges or just other members :D

https://www.planetminecraft.com/server/greenleaf-creative-1-13-2-creative-community-server/

The offer stands, but if it's not something for you, then the only thing I can do is give you a link to an old guide about Depth I did for another PMC member :D
https://imgur.com/a/P35Y9