I like doing a mix of things, tech skill videos, asking people more knowledgeable than myself, watching tournaments, if you have a good enough PC and good enough internet 20XX and netplay. The part nobody wants to hear is you have to grind out certain tech skill techniques. You have to get consistent enough with them or when you play you're going to be too afraid to try it bc messing it up often leads to you getting punished heavily.
Preferably I like to play with a friend. I get bored fairly quickly practicing one thing over and over so I try to practice often even if it's in small doses. The more comfortable I get with a technique the more I naturally use it. My friend likes to practice tech skill too so it makes it more enjoyable when we are just both practicing and chatting. Then we can play a few casual matches VS each other. A training partner if you can find one helps. A group is even better. One player alone may not punish a bad habit you don't even realize you have. So if you can get that variety of players it can help make you less predictable.
If your area has locals you can get to people are always willing to play friendlies and offer advice.
There are a lot of various tools at your disposal but try to find what keeps you both motivated to improve and still having fun. If you can meet those two criteria you'll get better for sure.