You're primary, yeah? I'm not so hot on specific primary techniques but behaviour management was really a massive weakness for me in the first half of my training year. The things I learned are:
Don't give up, ever - the kids will respect you for it eventually. (Took me 2 years with my bottom set year 8s into 9s, but by the end I was actually missing them when they did their options!)
Rewarding the positives, like River said, really works, but perhaps takes longer to have a visible effect than punitive measures.
What's the view on phoning parents in primary? I found that very effective (with certain pupils), but I don't know if it's the done thing
NEVER let kids talk while you (or anyone else) is talking. Once you start doing it you'll find it very difficult to get them back. This is probably the most fundamental thing, and once you establish the rule it's easy to maintain, but it's very hard to win a class back if you haven't been strict on it from the start.
Maybe take time out of a lesson to re-establish your ground rules, rewards and consequences with the class? And keep referring to them - get a poster with them on so there's a visual reminder. Praise any kid that does any of them right, massively, with a huge, genuine smile.
RELAX. Don't take it personally. This is really hard to do. I was so uptight all the time, but when I learned to chill the **** out about the little things a bit more, I established better relationships with the tougher kids and it was easier to work with them.
Aside from that, what does their normal class teacher do?
For me, things improved 100% as soon as I got new groups in my NQT year. I could take the masses of stuff I'd learned and actually put it into practice and it worked!
However, I did keep some classes from my first year, and I still had to deal with the same problems with them all through my NQT year, but because it was only 4 hours a week rather than nearly every hour on my timetable it was much easier.
Btw, sorry if these are really obvious or patronising things to say
It's just they seem so obvious now but at the time I was tearing my hair out over it all.
EDIT: your raffle ticket thing sounds really good, just make sure to be consistent with it. I started so many gimmicks that I just lost track of and they tailed off and the kids get pissed off if you don't follow through!