Sounds to me that you've already got the plan sorted. Stop eating crap and eat (somewhat) healthily and I dare say a bit less, and do a reasonable amount of exercise - and over time, good things will come.
Whilst I'm no expert, I'd be very sceptical of novelty diets (eg Atkins, or special supplements), but stick to a sensible amount of sensible food and you can't go far wrong. Losing weight slowly is almost certainly far better for you than starving yourself thin all of a sudden - which would also probably limit the exercise as you'd be knackered all the time.
Obvious stuff like cutting out beer, junk food, fizzy pop, sweets etc is obviously "a good thing", as is more fruit and veg and more "wholesome" stuff generally
Whilst I've always been fairly thin, I did find by simply cycling to work (round trip maybe 15 miles) fairly briskly and (continuing) to eat somewhat sensible lost a couple of inches off my middle without any real sacrifice, and though I wouldn't say I had a weight problem I was spreading a bit due to middle age and general laziness.