I think... that understanding of chess principles, and a thought process will probably move someone from XXX to 1XXX.
meaning.
I don't think the list of skills changes much in "club" level chess playing.
as to what that list IS specifically. people have laid out both huge and little lists. but it is mostly the easier aspects of chess---
- observing, avoiding, and playing tactics
- being aware of complications, and staying out of them is wise
- Keeping your peices active and safe
- Keeping your king safe; yet active in the endgame
- basic endgame ideas (though in the club level perhaps you don't have to obsess about the endgame to be a club player)
- being able to adapt to your opponents ideas
there's a list....
If you were to ask what, I think made the most difference.... Tactics! tactics,tactics and more tactics. you need to do them so much so often they are easy peezy. when a set of reasonable tactics looks very easy, you start seeing them in the game. they stand out to you BEFORE your into the winning fork or the unstoppable discovered check. you need to practice them, even if you can solve them. get to the point where you can solve them faster...
at that point, your moving up. I'm reminding myself that I've slacked off lately.,.. perhaps my library of tactics is dusty and thats why I'm stuck here at 1500....
We all start with a default rating of 1200.
Between 1200 and 1500, what things helped you win and move up to about 1500?
EDIT: I'm talking standard time controls, but if you want to include blitz that's fine too - just say it's blitz, though, so I know what you're talking about.