I have come to live and die by my grocery list. If I don't write it down, I will completely forget to pick up that item. It has also helped me keep on point and not buy too many impulse & duplicates purchases - I used to end up with a basket of crazy things when I just shopped off the top of my head.
Ditto! Totally lost without my list and to avoid a basket of crazy stuff as i check out, I make sure to leave DH and our sons at home...which saves about $100 alone.
We've got an Aldi's right down the road from a Giant. I usually hit Aldi's first and then supplement with whatever else I need from Giant. Once a month we hit Sam's, which is a bit of a haul for us but that's only for major stock up items.