Aside from that just keep doing what you're doing and revisit your old code every so often, you'll be surprised by how bad it is and you'll always find ways to improve it.
There's so many resources that I get stuck in the paradox of choice. I can't try them all so I wish there was a Top 5 or 10 list like master guide to learning SQL, Javascript, master guide to programming fundamentals/building blocks, etc.
For example, if I wanted to build the front end of my program- I don't know whether I should build it in Javascript, Django, or Flask. Even when I had to figure out what sql database to use- it seemed like there were so many choices.
For databases I recommend this book http://it-ebooks.info/book/866/ 7 databases in 7 weeks, generally though all you need is either mysql or postgres.
For front end work I would use Javascript not python. And I would suggest, and this goes for actually everything, learn the language first NOT a framework.
Too many people do it the other way round and get stuck with mental models they can't shake.
This is a good starter on Angular https://www.ng-book.com/2/ and the same style for React https://www.fullstackreact.com/
You've already taken the most important steps by building something that's useful, so don't get discouraged and just keep doing your best.