Hi there Mommy
Now, THAT's a tough question to answer "what plan to try". First thing that comes to mind is something Yoda said in one of the Star Wars films...
"Try? There is no try. There is only do or not do."
I think what I'm attempting to say here is...first thing to do is start researching. There are 1,000,000,000,001 diet plans out there...you need to find one that you can stick with for life.
If you're going to read ONE BOOK, I would HIGHLY recommend going to your library and looking for "Fat of the Land" by Michael Fumento. It's slightly outdated (published in 1997) but has some great insights and also just might help you in separating the 'good' plans from the 'bad' plans.
Also, I do encourage you to start JOURNALING. Get a spiral-bound journal book (I like the ones that they sell at Old Navy!) and a pen and start writing...get some insight on yourself, because bottom line, it's not the plan you pick that is going to take the fat off, it's YOUR efforts.
Another excellent exercise is to spend a few days writing down everything that you eat - EVERYTHING, down to that last crumb. The trick is to become MINDFUL of what you eat. Oftimes, we just eat automatically 'because it's there' rather than because of true stomach hunger...that's what makes us fat.
Here's another tip: Rather than saying "I'm gonna lose all this weight" (this is if you have a lot of weight to lose!) set a smaller goal...say 10% of your bodyweight. Let's say you weigh 200 pounds...so set your goal to lose 20 pounds...through healthy eating AND exercise (exercise DOES play a part, but as stated above, if you eat a ton of crap all day, you're not going to lose fat). After you lose that 20 pounds...before trying to lose more...MAINTAIN that weight for a few months, maybe six months, before attempting to lose more weight - then shoot for another 5-10%, then hold that weight for a few months, etc.
I will tell you this from personal experience...if you think LOSING weight is tough, maintaining the weight loss is just as tough if not tougher, unless you make PERMANENT healthy lifestyle changes. (That's the problem I have with the word "diet" - it implies a temporary eating change only). Setting small weight-loss goals, then maintaining them for awhile before going to the next goal, IMO teaches your body to maintain at the 'new' setpoint and you're less likely to rebound and gain your weight back.
Another thing - "Accentuate the Positive"! That means look on the positive side...the glass is half-full, rather than half-empty. Instead of saying "I don't have the willpower to do this" say "I CAN do this!!" and put your goals down in writing. Make sure you write down what you want to do at your new lower weight...go horseback riding...snowboarding...buy some new clothes...have a romantic night out

all the stuff you dream of doing (sorry about putting horseback riding in there...that was a major dream of mine and one that I would have never ever done at 265 pounds...but now I'm taking lessons and LOVING it...beginning jumping...fun!).
Just a few tips...oh and here are some awesome websites...
http://www.stumptuous.com/weights.html <== Krista Scott Dixon's Weights for Women site. GREAT info there!
www.skinnydaily.com <== Just discovered this yesterday. check it out - JuJu also has a forum here at 3FC.
And if you're looking for me...I generally hang out at the 3fc Ladies Who Lift forum...feel free to come have a look 'round! Take care - and remember YOU CAN DO THIS!!