One thing I would definitely do is prioritise SQL from the start.
SQL is an essential tool in any web developers toolkit and touches upon almost everything you do in this area. Thus far I have dodged the problem by using Entity Framework to abstract away working with databases in Asp.net, but obviously that is of no help the moment you want to use something other than C#.
After all, I believe C# is complete overkill for the needs of most business web applications, it’s like using a cannon to crack a nut.
So here’s what I would do:
- Complete the Analyse Data with SQL study plan on Code Academy.
- Start doing the SQL challenges on https://www.codewars.com, they range from the very elementary to extremely advanced. This is a good place for practicing the basics
- Do the leetcode “SQL 50” study plan
- Alongside all the above, make a local SQL database from first principles and integrate it into a basic web application.
Done that? Now you have a useful command of the basics.