One of the reasons people "fail" at weight-loss is that in order to effectively lose weight, you have to change a whole bunch of behaviors. Depending on the program you follow, you'll be eating different foods, or the same foods in different amounts. You'll be moving more, whether by adding more physical activity to your daily routine or doing a more formal exercise program. You'll be keeping track of what you do and how it works. All of these are habits you hope to build. You may have more habits on your list.
The problem is that it's really hard to build one habit, let alone several at once. It's been shown that it takes about three weeks to build one habit. So, how long do you think it takes to build a bunch of new habits? I have no idea, but I do know that you can't do a whole bunch at once and be successful, long-term.
The best way to lose weight, especially if you have a lot to lose, is to build new habits one at a time. Pick one. Do it for a month, even if you don't lose weight that month. (Which you likely won't, if you pick writing everything down as your one habit.) Then, pick another and do it for a month. Why a month, if it only takes three weeks to build a habit? Two reasons--to cement it into your brain and because it's easier to keep track of a month than three weeks.
"But," I hear you say, "it will take forever to get the weight off if I don't do the whole program right off the bat." Well, yeah, it will mean taking longer to get it off. But, it will also mean you're more likely to keep doing the habits and keep it off. Since keeping it off is really the goal, building habits you can keep doing is more important than taking as much off as you can, as fast as you can.
Oh, and why did I put "fail" in parentheses in my first paragraph? Because you've only failed if you've given up forever. Each time you pick yourself up and get going again, you've proven you're a success. So, you're all successes just for being here and doing what you're doing. Good luck!! :)