How do I improve my programming skills without having to join groups and going to YouTube more often? ?

Answer 1

source of knowledge can come from your own experience. That is why Sololern gives xp to user who gain their experience from course, code playground, Q&A, and challenge.
you can improve your skill by gaining more experience. it can be months to years.
Eventually, you'll get there.

Answer 2

lots of practice :)

Answer 3

Master C and create your own libraries and your own Unique language. Without needs you can't learn. Without internet, debugging the old programs is the only solution. But U should know how to debug. Its better to practice session by session, based on needs.