No. We don't hit in this house.
1-2-3 Magic: child gets 2 clear warnings about stopping unwanted behaviour, and then consequences ensure. These can be removing child from situation and dumping somewhere to calm down (not a Naughty Step here, just another place which is safe). Removing me from the situation so he no longer has me to rile him up with, etc. Never pleading, never reasoning. We are the grownups, we don't need his approval to parent him. And we never hit. Nor smack, spank, tap, whatever it's called. I don't want him thinking it's ok to hit people smaller than him, it's my job to model good behaviour.
We are considered pretty strict, insistent on please and thank you, nudging him gently towards sharing, and DS is big for his age so I am constantly reminding him to be gentle with others. That said, he has a total meltdown over nothing quite often. Sometimes he'll scream and rage and weep real tears in response to "DS, do you want some apple?" - this morning he staged a 2 minute medley of my greatest tantrum faves because I offered him cereal and he requested a hot dog, which I then refused. The way I see it, if he's having a screaming meltdown over being unable to eat a certain food for breakfast, my job is to calm the situation down, not inflame it further by hurting him. If I'd smacked his legs at that point, he would have screamed harder and for longer. By picking up the cereal and walking into another room with it, then sitting down with a story, by the time he'd followed me from the kitchen to the sofa, he wanted to sit on my knee and read the story, and then eat his breakfast.
It's not psychological warfare exactly, is it? 
I'd never claim I haven't wanted to give him a good smack when he's being difficult. I'm not smug, I'm not perfect, and he can be a nightmare and it's bloody hard work. But smacking would (1) teach him something I don't want him to learn (mummy hits to get her own way, but only people smaller than her), (2) not actually make me feel better, (3) probably cause DH to leave me and take DS with him and (4) make whatever tantrum/bad behaviour situation we're in, worse.
So why bother?
yes, I was smacked as a child - and shouted at - and no, I'm not miserably damaged by it. But I do remember one incident when I was about 5 or 6 thinking "you big bully. Why is it ok for you to hit me and not me to hit you?" It did make me respect my mother less. I'm trying to model the kind of behaviour I want DS to use, and 'if you're at the end of your rope, hitting is ok' is NOT the kind of thing I want him doing .
Even if I feel like it sometimes, there are other, more effective ways of dealing with bad behaviour.