Just some things that I've learned the hard way. I was once up to 270, and at 5'9'', that ain't good. I got down to as low as 160, but I didn't like how I looked because I sacrificed a lot of my lean muscle mass in the process, so I put some weight back on. I'm at 205 right now, and I'm happy with where I am, but I do want to lean up a bit.
Don't think of it as a 'diet', because you may put yourself in the mindset that you're going to exclude a lot of foods. That's not true. You can still have the foods you like, either modified slightly, or just once in a while. A lot of dishes and foods can be modified to be lower in fat, higher in protein, higher in fiber, more veggies, whatever. Something's fried? Broil it, or sear it, or grill it. Sometimes it tastes just as good or better.
Portion control. Eating smaller meals more frequently during the day will help you stay fuller, and with more meals comes a larger variety of foods to eat, so in a sense, you have more of a choice of what to eat.
Have a cheat meal or day. We all have cravings. Set a meal or day to have those things you really like, but don't go overboard. Take everything in moderation. This way you won't think that you cut something out forever, and if you change your eating style drastically, having those "normal" foods will give your digestive system some ease in coping.
When you change your eating style, do it gradually. If you drink whole milk, switch to 2%, then 1% and then finally skim milk.
Keep a journal of what you eat. I don't do this, I don't know why, but others that have do so in order to see exactly what they are currently eating and then figuring out what they need to change. It's like constructing a game plan. Once you see what you're up against, you'll know what you need to change and how.