Don't worry TOO much about what you're eating (but obviously aim to eat more of the healhty stuff) but cut down on portion sizes. Don't have a huge bowl of pasta, cut down the size. I've lost weight despite not being able to exercise, mainly by cutting down on portions. I've also seriously reduced my alcohol intake.

Steer clear of 'diets' - if you feel like you're depriving yourself of stuff that you want to eat then you'll feel resentful and fall off the wagon. So eat what you like, but only small amounts of naughty stuff.