How To Lose Weight Forever

I want to lose a lot of weight now and over summer. Can anyone suggest a workout routine and diet for me?

I am 16 years old, and going on holiday in a month. I want to lose weight before then, and also continue to lose it after my holiday!

I’m looking for a suppliment taht really helps with weight loss and muscle building, that really works. I already lift weights I just want a helper.