All of what the above have said about calories in vs calories out! Stay well clear of any restrictive diet plans or weight loss pills.
The best method is consistency. There's no super quick fix to losing and keeping the weight off- if you go back to old habits after you've lost weight then you'll just put it all back on.
I guess there's two sides of it- eating and exercise. In terms of food, you don't need to do anything extreme. Try making a few healthy swaps like if you add sugar to drinks or drink a lot of sugary drinks, reduce the amount. Increase the amount of veggies in meals. Personally I don't eat after 8pm because I struggle to stop when I hit the snacks at night. Aim to find a way of eating that keeps you satisfied. You don't have to cut out biscuits, cakes, sweets etc., just try and keep them in small amounts if you want them rather than a big blow-out 'cheat meal' (or day) once a week that's likely to end up throwing your calorie deficit out the window.
Exercise also doesn't need to be extreme. You just need to move more. Running, going to the gym, following workout videos on youtube at home, vigorous cleaning, going on walks....if it gets you moving it all counts!
Depending on your start weight, losing 1-2lbs a week is generally considered a safe rate. If you're quite a bit overweight then the rate may be faster, if you're not that big then loss will be slower.
Above all else, be consistent in what you do to build good habits and know that weight loss takes time and your weight naturally fluctuates so expect to see some rapid loss at stages, some plateaus, even some increases (if you eaten a lot of salt for example, your body may retain liquid. It's temporary, don't let it throw you off).