It could be down to your diet. I find processed and salty foods bloat me up (such as ready meals and white bread). Try eating multigrain bread and brown rice instead and get lots of fibre through veg.
Funnily enough, I find the best thing for getting rid of bloating is beans (kidney, black eyed etc - not the ones in tomato sauce). Although they have a reputation for making you - erm - gassy, I find the day after having something like a veg and bean chilli my stomach is flatter. Meat can also be a bit difficult to digest if you are prone to bloating, so I cut down when I'm bloated.
It could also be a bit of water retention so make sure you get your eight glasses of water a day and cut down on coffee.
Fizzy drinks, smoking and swallowing a lot can pump extra air into your guts, which will make you bloat, so avoid these if possible.
Finally, you could try pysllium husks (from all health food shops) - you mix them with water and it looks and tastes like wallpaper paste but 'sloughs' the inside of your gut and keeps everything moving!