I am so OCD when it comes to my shopping list! I actually make a first draft, then I revise it and make the final list that I take to the store with me.
First, I take a look at what basics I need. Things like coffee, sugar, bread, juice, creamer, etc. Then, I look at what I have. Once I have a mental inventory of what items I have, I check the sale paper and my coupons. Once I've done all of this, I come up with recipes for 5-7 meals. Sometimes it comes from me, sometimes from a recipe book or magazine. As I decide on each meal, I add what I need to the list. When I am done with that, I have two lists. One is meals and the other is my grocery list. Then I re-write the grocery list in groups based on the layout of the store. This way I rarely forget something that I really need, and I zip through the store quickly.
Plus I save lots of money by using the coupons and sale items.
Yeah, totally OCD, but it works for me!