Calories

I suggest you to count your calories intake everyday.it is better if you will eat raw or fresh vegetables when having a snack or you can buy 100 calorie snack in the nearest supermarket. You should also drink at least 8 glasses of water every day and don't forget to exercise. Avoid eating sweets and junk foods as much as possible.

Find any number of online calculators, plug in your info, take number given (TDEE) and eat % less than that number for desired weightloss (shoot for .5-1% of bodyweight as weekly number for loss). Run with that number for a couple of weeks, take average weekly weightloss and adjust calories up or down in small increments accordingly.

So for example, if you come up with needing to eat 1500 calories (just using this number as an example only and nothing to do with your stats) daily and do this for 3-4 weeks, if at the end of that period, you lost 1-2lbs on average weekly, then you are golden and found your sweet spot. If you have lost less or maintained, then drop calories by about 50 or so and run another few weeks. If you lost kore than 2lbs, then you might want to increase calories by about 50 or so, but do these changes in small increments. Takes time and patience.

Note: this is a little different than how the default method of MFP does as you will have to account for activity logged back to eat back those calories, where the TDEE method takes into account your activity already, so you just eat the same (or about the same) everyday. Some people find this easier and more consistent, but that will ultimately be up to you.

You do understand that this tool will calculate all of that for you right?

It's not just calories, it's what you eat.

For example, I would highly recommend to someone trying to lose lots of weight not to eat a donut and drink a sugary coffee drink for breakfast.

Once you get down to your ideal weight, you can eat donuts again. But keep weighing yourself to make sure you don't yo-yo back to your original weight. It happens all the time.

Weightloss and health are not necessarily the same thing. The OP's question had to do with weight-loss which is a simple matter of calories in vs calories out. From what source those calories are derived from is moot in regards of weightloss or weight gain. If you meant to address her health, then yes, there are food options that offer better micronutrient and balanced macronutrients for better health.

I would calculate your BMR and sustract 500 calories (that way you'll be losing a pound a week. Make sure to eat enough protein for muscle (that way you'll burn much more calories), vegetables for fiber (to feel full with less and that stuff), and just stay active.
Eat frecuently for your metabolism to speed up and don't forget to drink TONS of water (but not too much or you'll suffer from water weight)

You should not encourage people to eat below their BMR. Did you perhaps mean TDEE?

Eating frequently has no effect on metabolism.

It's not just calories, it's what you eat.

For example, I would highly recommend to someone trying to lose lots of weight not to eat a donut and drink a sugary coffee drink for breakfast.

Once you get down to your ideal weight, you can eat donuts again. But keep weighing yourself to make sure you don't yo-yo back to your original weight. It happens all the time.

Nothing wrong with eating a doughnut or having a sugary coffee drink while maintaining a caloric deficit.

Depriving yourself of particular foods only for as long as you're losing weight does not sound like a realistic way to maintain the losses you worked to get.