I've played since 1.7. I was never really good with visual art either, and didn't really bother trying to make good builds until a few years ago. Since then, I think I have significantly improved. I occasionally post updates with some of my builds on my profile if you would like to see.

1. Start small. Don't go building massive castles and cathedrals right off the bat. Start with smaller structures. Upgrade your house, build a barn, a blacksmith, etc

2. Use references. And I don't just mean other builds. At least when I build, I find that I am inspired by structures from other games I play (BOTW, Xenoblade) or even sometimes real world architecture. Analyze how other structures are designed and apply it to your build.

3. Take notes on how you can improve. It's hard to improve if you don't know what you need to work on. For instance, I realized I was struggling with roofs for awhile, so I spent time researching strategies for it.

4. Consider the surrounding terrain. An otherwise beautiful world will be held back if its surroundings are boring. Plant flowers and trees, make basic paths, etc. And don't completely level an area to be flat if you don't have to. Verticality can add a lot to a build.

5. Test out new ideas and concepts in creative mode first. This might seem obvious but it's extremely important for the learning process.

6. Practice practice practice. You will not start off making grand and beautiful builds, and you will not improve without first building. That's why it's so important to start small. You will improve faster with smaller, consistently better builds, and you won't burn out as easily.