I think, if you want to improve, you should be:

1. Playing often 
   • That's the most important thing.  Once you are doing that, then try:
2. Doing a bit of study of (a) openings, (b) tactics, and (c) endgames. 
   • I seem to remember there are some fine books about these things for juniors.  
   • Study can be reading books or doing puzzles or watching videos.
   • Once you are studying as well as playing, then start:
3. Writing down all your slow-play games (and others if you can), and then:
   • Going over your games, (a) by yourself, (b) with another player, and/or (c) with a computer
   • Checking your opening moves against a book or database - who made the last 'book' move

If you aren't doing any or all of those things, you won't improve as fast as you could.

We also have some advice about:

• Opening advice
• Daily Chess Puzzles
• Middlegame Tactics
• Middlegame Strategy
• Endgame advice
• Get your eye in

We have some things to look at from training events (see below).

And we have some advice each year for the Devon U14 County Chess Team.