IMHO, bet size depends on your stack, style (tight or loose), position and table size.
I prefer "open raise" 2BB+1BB for each caller in tournament with deep stacks and 3,5 BB for stealing blinds.
Flop is determining bet bypass your role on preflop: If you made open raise, you should make countbet with size 1/3 of bank.
Next streets is theme of many books ))