We try to stick to natural consequences for the more minor misbehaviours
For more "serious" ones, After a lot of trial and error, I realised both children needed different "punishments" (not keen on that word)
I use 1, 2, 3 Magic for ds1 (6) he's the type of child who starts misbehaving when he needs some time out on his own, peace and quiet and time to get himself together. If I get to 3 then I (and he) know he needs to go to his room. He'll read or rest or play with Lego then come out when he feels ready usually for a hug and to apologise.
Ds2 (5) is the complete opposite, when he misbehaves it's usually because he's feeling sad/upset/insecure/tired whatever and so I'll scoop him up and sit with him facing me on my lap and just cuddle him. Once he's calmed down we have a chat about the behaviour.
It seems to be working well for us, there hasbeen less fighting between the kids, they are more likely to use words rather than just lash out, sometimes ds1 will take himself off to his bedroom when he starts feeling angry or frustrated before I even need to start counting and ds2 will come and tell me he needs a hug.