Punishment is really quite simple, take away from them something they love and make them earn it back by good behaviour.
Can be anything from, after school activites, bedtime stories, tuck in's, favourite toys, trips to the park, tv, computer games, later bedtimes for the eldest one, days out with friends, sleep overs, one on one time with mum or dad etc etc. It can be anything, it will bother them eventually if they keep losing things they love.
Dont get angry with them, just be firm with your requests, warn them once and then carry it out! You must carry it out.
Its exhausting for the first few days but you'll be amazed at how fast they'll pick it up. Basically let them know that dad doesnt mess about.
If people think your too strick then your doing a great job ;) Oh and get some me time, find your 'man cave' and spend some much needed time their. Put your kids to bed by 7.30 and have an extra 30 mins for you.