I am 5'4 and about 7.5 stone and I eat around 1,200 calories per day. The trick is to eat a high protein/veg diet. I find that when I am eating a lot of protein I don't get hungry in between meals. A daily meal plan for me would be for breakfast, two eggs with mushrooms, spinach, tomato, a little goat cheese and some greek olives. For lunch, a big salad with spinach, greens, broccoli, peppers, tomato, cucumber and then a protein (steak bites, chicken or salmon), olive oil and a squeeze of lemon for the dressing. For dinner, a protein (chicken, beef, fish) with lots of vegetables and a green salad.
If I am craving something like bolognese, I will substitute the pasta for kale or courgette or just eat the sauce (go heavy on the beef).
Things to consider when transforming your diet are to stick to whole natural foods. Vegetables are pretty low in calories and super high in nutrients so eat as many vegetables as possible (stay away from starchy vegetables like corn, potato, etc). Cook with fresh herbs, fresh garlic and onions to amplify flavour. I never eat anything that is labelled 'low fat', I only eat things that aren't super processed, full of fillers and chemicals and sugar. I drink my coffee and tea black, never use salad dressings (olive oil and a squeeze of lemon is healthier and taste better in my opinion). If I am craving something sweet, I will have a piece of fruit in the evening. Baking apples with cinnamon are really tasty and take cravings away. I also really like to do a small berry smoothie with greens and almond milk if I am craving sweets.
I try to only eat grass-fed meat and buy grass fed butter so I am eating clean/healthy meat.
I rarely drink alcohol. I love a really great glass of red wine but I save that for special treats, like going for a nice steak dinner in a great restaurant. Other than that, I don't drink. You should treat yourself with the very best, instead of filling your body with cheap sugary drinks, diet foods that lack nutrients, etc.
One thing to remember is that this should be a way of life, not a quick diet that you only try until you reach your goal weight. Eating healthy shouldn't be viewed as something to be tolerated or that you are forcing yourself to do. You can create a lot of lovely, easy and tasty foods that are high in nutrients and very filling. And when you are eating healthy the majority of the time it won't matter that once a month you have some crips or lovely dessert on a fancy night out.