As said a little bit ago, hold off on starting your promos. Play more, get comfortable with the game. Know about 2 champions per position. You don't want to rush into it and be stuck in bronze for the whole season.
Just keep playing and if you're good enough you'll get out. It's only those who are stuck there that complain; what do you think that means?
I've dug myself out through playing, went from Bronze IV to Silver V last year
This year Silver V to Gold IV
Just keep playing and practicing to improve yourself as you're the only constant variable when you play games