What diets are good what are bad?

I want to loose 74lbs. I am very overweight for my age and height. I hear so many good things about some diets then turn around and I'm hearing a ton of bad stuff too. I was looking into the south beach diet and was loving what I read then I turn around and people are saying it's a crock. I would love to loose the 74lbs by Feburary which is two almost three pounds a week. I know I can do it. My mom needed to loose over 100lbs and she was loosing 3-5 even sometimes 6-7lbs a week on some occasions by excersizing and having her own specific nutrition plan but I want to have my own and know what will work for me. Any ideas or suggestions? I got those acai berries too by the way just to see if they'd work.