My son is a bit older (23 months) but what we do when he hits is:
1. Over-react to the pain of hitting "Ow! That hurts Mommy"
2. Sit quietly with him, holding his hands in his lap and slowly count his age in months interjecting "No Hitting" every 5 count or so.
3. Make him say/sign "sorry" (that took awhile, as his vocab grew. I would say "can you say sorry?" first he would just make a sad face, then he started responding with "yeah", now he signs it and occasionally says it.)
4. Hug & kiss, release.
This all takes less than a minute total but he does not like having his hands held at all. When he kicks we hold his feet. It has really helped curb his hitting and kicking. We started it when he was 18 months old and we were doing it 5-10 times a day and now it is maybe 1-3 times a week. We tried time outs and he did not understand what was going on. He would do the time out and get out and do the same behavior again.
We've also spent time teaching him "Nice & Gentle" touch, but we do this at a different time - not when he's mad. We'll touch his face or arms lightly and show him how to do the same to us, or his toys or whatever is nearby. So now when we see him going toward someone in anger we only have to say "Nice & Gentle" and he *usually* will pet them instead of hitting.
Since all kids are different you just have to experiment with all advise you can find see what works for yours.
Good luck