Everyone's situation is different, but like others have said the basic rule is calories out > calories in = weight loss.

I made relatively minor adjustments in my diet that have been sustainable, cutting out the obvious bad stuff. I made relatively minor adjustments to my exercise regimen, adding a 30 minute workout daily. I figure as long as I'm continuously losing weight, the rate doesn't matter. 30 pounds over the last 6 months is just fine with me.