Some principles that can help:

• Psychological Component: Your diet needs to not only be physically, but psychologically maintainable. If no diet is psychologically maintainable, you are weak.

• Calorie Economy: You will only lose weight if you're consuming less than you're burning. There are loads of calculators online to estimate how much you burn a day.

• Law of Averages: Number trends are important, while individual measurements are not. Track your numbers (weight and waist in specific) under the same conditions each day and compare weekly averages. If your weekly average hasn't changed in one week, that's nothing to sweat. If it hasn't changed in two weeks, it's time to change something in your program (i.e. eat less).

• Macronutrients: Carbs, protein, fat. None of these are inherently evil, as much as some sources will have you believe. That being said, proteins have the highest satiety effect, meaning you'll feel slightly fuller by consuming higher protein. They also have a higher thermal effect of feeding (TEF), which means that they takes more energy to process. So if you consume 150g protein in a day, your body will burn ~100 extra calories just to process that. Slightly lower fat is good simply because fat is 2.25 times as energy dense as either carbs or protein. However, if you go too low fat it can mess with your hormones.

• Track Yo Nutrients: Weigh and record everything you eat. That way, you know exactly how much you're hitting/missing your goals by. (Note: This can drive some people insane. As long as you're not of that mental disposition, I suggest tracking.) People often under report calories if asked to do so after the fact because they selectively remember the times that they were hungry instead of the times they stuffed their faces (hardgainers do the opposite).

• Solid Advice: Try and only consume solid foods. Drinkable calories won't fill you up as much, and you'll be hungrier. Along with that, if you prioritize calorie-dense foods (things high in fat and sugar), you will be hungrier.

• Time Tables: The only time table that matters is yours. It doesn't matter that you saw some guy on the internet drop 50 pounds in 20 weeks. You're not him. If it takes you 40 weeks to lose the exact same, guess what: you're nowhere near as fat as you were 40 weeks before. You're not going to stop working just because there exist other people who make more money than you do.

• Devil's In The Details: I personally give myself a macronutrient profile for each day (today it was 265 C, 185 P, 55 F), then record the numbers of each food item as I eat what I want. Other people might find that tedious, and they'd prefer to figure out every meal the day before, or figure out all the meals they're going to eat for the week on Sunday. Do what works for you, but have a plan.

• Feeding Window: One thing that really helps me is intermittent fasting. A typical split looks like 8 feeding hours and 16 fasting hours in a day. I personally do like 1-4 feeding hours because I'm a pig who eats all his calories in one meal. There are a dozen benefits to this, but specifically in response to what you said, it prevents me from snacking or having random meals that break my diet. I just say, nope, I've already eaten all my calories today. I don't have to worry about whether a snack is sending me over or not.

• Lift: Lift.

There are a bazillion other things that could be said. These are some principles that have helped me. I'm getting to that stage in my cut where I'm starting to get a couple veins on my abs, so that's pretty exciting.