Stick to one credit card if possible. That way you won't spend as much. Use credit card that rewards you so for every dollar you spend, you'll get something back. Better still, leave that card behind and stick to cash.
Don't go for the Zellers or the Bay or Sears card... they just make you buy stuff you don't need. (I really HATE them asking me if I want one each time I purchase my items. Enough already!)
Get a grocery list and STICK to them. It's hard to do but I find that if you stick to the essential items ONLY, you won't overspend. Indulge in other items once a while but let's face it... do you really need mangoes or that chocolate bar each time you go shopping?
Keep an eye out for coupons. I go crazy for flyers (go online to get them, save the trees!) or join forums that will let you know when there's a good deal.
Bulk is the way to go but it's not always practical. Still, if you have a friend or two, you can go bulk hunting and share out the cost.
Buy fresh produce when possible. It's amazing to see the cost difference when you compare something that comes pre-package to something that isn't. I know where to find cheap eats and know a bargain when I see one so I buy on the spot.
