How to improve without a coach ?
Play rapid games with increment.
Analyse every game you played before starting next game.
Remember mistakes you did and try not to repeat them.
Solve tactical puzzles at least 20 - 30 minutes daily. Do it correct way, which means try to calculate till the end without guessing moves.
Study games of old masters like Morphy, Tarrasch, Capablanca, Botvinnik etc.
Do it every day and you will slowly but surely improve.
I just play 10+0, and review my games. Though if I was taking chess seriously I would do that + 30 minutes to like an hour of puzzles a day.