Good for you for making the decision to take good care of your health! I suggest making small changes at a time. If you do anything extreme, your results will be too hard to maintain (and may not even be healthy).
What may work for one may not work for another. The above poster, Bill, suggested not eating between meals. This works for some people, yes. For me, I am the opposite. I eat small things throughout the day. See what works best for you. I'd rather eat a small meal, then have a small snack later on. It should even out in the end! I tend to get light-headed if I go too long without eating.. and then I accidentally overeat if I'm super hungry. I try to never get too hungry or too full, just in between.
Try making simple changes like swapping out unhealthy foods for better choices. One thing I did was try to add in more fruits and veggies and swap out unhealthy snacks and treats. I also added plenty of water, since I didn't always drink enough.
Add in some exercise with your healthy eating. You can start with something easy, like walking. Walking is great because it's not tough on your joints. It also helps with stress!
Best of luck to you