I joined Weight Watcher's at the end of January this year and lost fifty pounds. I have gained and lost the same fifty pounds about twice before so I am not going to make the mistake ever again... I have realized that it just isn't worth all the hard work to not maintain so great question!!!!! I am sure I am older than you because the majority of women on this site are young moms but I love it here just in case I can spread some wisdom around and I have to say young women with a fresher perspective have taught me recently too!
Sooo after you have reached your goal... it is so easy to stop logging or journaling what you are eating...if you joined a group like WWs, it is so easy to start skipping thinking you "know" everything now... and if you joined a gym it is easy to make excuses why you can skip there too...
My tricks have been....
LOTS of water. I carry around a 44 ouncer and fill it at least 4 times a day. Water in... calories out... I also try to really know what I am eating. I can't say I write it down religiously like I did the first 50 pounds but a half a cup may not be exactly what you are eating...measure whenever possible!!!
Fruit is free on WWs now when counting your points... I thnk they made it free cuz we all would rather have a piece of cake or a cheeseburger rather than getting in our 5 servings of fruit and veggies a day! Choose the fiber over the carbs! But try to eat healthy! Have one day off where you eat whatever you want but within moderation. Try not to eat past 7PM etc... I walk at least 2 miles a day when I am really on program, skipping maybe two here and there but really try to walk at least five times a week. And I just joined a gym to tone it all up! And I have been going about three times a week... Remember it takes less time to regain than it did to lose! You were worth the time and effort it took to invest in a new you.... you are worth the investment to keep up the good work! As far as calories consumed you can go on line to Weight Watchers and I don't think you have to join to find their recommendations.... for your age, height and weight and to maintain it... the average is 1200-1500 calories a day for the average woman but I follow a points system but I am sure you can google it!
Congrats on everything and remember nothing tastes as good as thin feels or at least only for a minute of enjoyment... verses the pounds... not worth it in the end! (I'm talking to me right now too!!!! I have grown too comfortable so thanks for this question!)
Keep up the good work!