I think setting reasonable goals (and figuring out a reasonable plan to achieve those goals) has been one of the most helpful things psychologically for me. Knowing that say, I want to lose 5 pounds this month, and planning to go to the gym 4 days a week and eat so many calories, (or whatever your plan to get there), it makes it so much easier to do well. So much better than the ambiguous "I want to lose weight" goal and not really having any way of acheiving it other than vague plans to cut down on pizza and fries and working out 'more', its a way to keep yourself accountable and I think you feel more accomplished when you hit your goal.
As far as actual tips to lose I've found that taking the time to figure out all the healthy foods I like, and making sure to eat them more often. feta cheese, jalapeno peppers, onions, scallops are some of the ingredients I've been making it a point to cook with because I love them and they're healthier than my old staple ingredients. Also, looking at what foods I like that aren't quite healthy and finding ways to make them better. hungry girl's website has a lot of tips to make things that aren't healthy better for you.
Also allowing myself to eat things I crave in moderate portions rather than depriving myelf entirely. its not sustainable to never eat your favorite things, just don't have a 1000 calories worth in a sitting and do it every night and you're going to be fine
