There is a lot of good advise here, but since the diet industry has never found a single formula that works for everyone and still stay healthy, you must find the diet that works for you.
For me, I eat 50% of my daily calorie intake as vegetables and 25% as fruit. Fresh is best, frozen is just as good. Canned fruits or vegetables are a last result, but read the labels for added sugar and salt. I avoid restaurant food as much as possible. They cook for taste not health. Some restaurants are good, others are OK, but a few are really bad. Who in their right mind would think that a 1000 calorie breakfast burrito is healthy?
Keep in mind that fats are 9 calories per gram, while carbohydrates and proteins are 3.6 calories per gram. Sugar being a carbohydrate is only 3.6 calories per gram, but those are empty calories. There is no other nutrition other than just calories. If your goal is to reduce weight, avoid sugar, especially hidden sugars. Read the labels.
Fats are concentrated calories. Yes we need some fats, but only a little bit. Every dietitian in the world will tell you to limit fats if you want to lose weight.
The amount of calories you eat daily really depends on the weight you wish to be. There are many online calculators that will help you compute you proper calorie requirement.
Good luck in finding what will work for you. I found my diet and I have lost just over 100 pounds. Any diet is not a short term fix. You must make a permanent change in your eating habits. After a while, it just seems natural and normal.
Lastly, I want to say something about digestion and absorption. Have any of us noticed that some people can eat anything and never gain weight? While other just look at food and gain weight. If you do not digest all your intake into something that your gut will absorb, then it will just go right through your intestines and the available calories will not be used. There is also a psychological component here as well. If something is appealing and smells good, it just seems to go down the hatch without us even noticing that we ate something. Also, daily stress will cause us to seek comfort food, that is usually high in calories even though we are not really hungry.
There are many factors in play here. We all just need to be aware of our individual needs and find the foods that are best for each of us.