Tip #1. Make lifestyle changes if you want your weight loss to be permanent. Going back to your old routine just isn't going to cut it any more.
Tip #2. Drink lots of water regularly. It keeps your body clean of toxins. Avoid caffeine, nicotine products and alcohol as much as you can. When with friends, stick to one drink if possible.
Tip #3. If you regain weight at some point don't go on a diet, instead change your eating/exercise habits so that you make permanent changes. Fad diets are temporary band-aid solutions. Never go on a diet with food/a plan you KNOW you cannot eat forever!
Tip #4. Take a cooking course. Learning to make more healthy foods at home and expand your knowledge of what you can make and eat will allow you to maintain your diet more easily by having a broader range of healthy food options in your repertoire.
Tip #5. Set a caloric intake maintenance range. Your goal now is to maintain your weight, not to continue losing weight or go back to your old ways. Set a range, practice it for a few months and check your results, and once you know that the range works stick with it. After several months it should already be a habit.
Tip #6. Avoid dining out. Unless it is a special occasion you should not be dining out. Restaurant food / ordering take-out is a very quick way to break your habits - worse if you get into the habit of eating out regularly.
Tip #7. Remember to snack between meals - healthy snacks like fruit, salads, nutty granola bars, etc. This was you won't be overly hungry and binge later. Binging = weight gain.
Tip #8. Keep exercising at least twice per week for 30 minutes. Just because you lost all the weight doesn't mean you should stop exercising. Pick your favourite exercises and keep doing them.
Tip #9. Get involved in more sports that you enjoy doing.
Tip #10. Try new sports or activities that you always wanted to try. eg. Archery, boxing, rock climbing, fencing, snorkeling, windsurfing...
Tip #11. Go outside on dates more often. Regardless of whether you are married or single, dating activities such as picnics, throwing a football around, long walks on the beach - now is your chance to enjoy your new physique.
Tip #12. Get a dog and take the dog for walks twice daily. The dog will keep you healthy and it will give you an excuse to go outside more often.
Again, congratulations on achieving your weight loss goal!
Also I want to note that you should avoid going further and LOSING TOO MUCH WEIGHT. That isn't healthy for you either. What you want to do is to maintain your ideal healthy weight. Not too much and not too little. Below is an example of what happens when someone becomes too obsessed with losing weight and loses too much.