How to shop smart on a limited grocery budget?

Hi so I only have $150 left for groceries and I was wondering can you guys give me suggestions to shop smart with what I have, it's not a lot. How do you ensure that you get what you need and not what you want? What should be the most important items I get?|||Check out "Poor Girl Eats Well" website. She has a lot of good advice and recipes. She also does $25 grocery shopping trips and lists what she bought. Good luck!!|||walmart