I find that action goals, like "I will eat on-plan for two weeks" (or just "for today" if you have to go day-to-day) are more effective for me than results goals, like "I will lose 20 pounds by September".
I can affect the actions. The expectation is that the actions will get me to the goal. But I really don't have control over the goal... not specifically.
I CAN control the actions that will lead to that goal -- eating on-plan, exercising more, or even more specific goals like eating 1400 calories/day, or fewer than 100 carbs a day, or doing calorie cycling for an average of no more than 1400 calories/day (or whatever your particular plan is).
And because my body often surprises me by its responses (or NON-responses) to the various plans I've tried, I've found a lot of encouragement in being able to say "I've been on-plan for five days" and then five days more, and then a falling-off, then on-plan for three days, etc.
Whenever I have set my goals as a result -- x pounds lost by y date -- I end up discouraged and blaming myself for being a whiney loser (and not the kind of loser I want to be!).
So my advice is:
- Find a plan that you think will work to begin
- Stay on that plan for at least one month without tweaks to see how your body reacts
- Set your goals to be action-oriented (I will do x) rather than goal-oriented (I will lose y pounds).
- Post here regularly for support and encouragement.
As to the type of diet... there are all kinds out there. It may take you some time to find the one that fits you best.
Personally, I'm pre-diabetic and insulin resistant, and am not on any medications... so lower carb works really well for me. I use the Insulin Resistance Diet framework (linking and balancing whatever carbs I DO eat to protein, and limiting carbs to fewer than 100/day), and JUDDD calorie cycling (a very low-calorie "dieting" day followed by a higher-calorie "normal" day, because plans where I am on restricted calories every day leads to burnout and binging for me). I also use "Brain over Binge" techniques to avoid overeating (or overdrinking, another of my many faults!).
I find these combine very well to keep my blood glucose level and under control... and still give me the calorie average I need to lose weight slowly, and the flexibility to allow me to eat out with my family, which is an ingrained part of my lifestyle.