Let's get going....
Rule Number One
At
ALL TIMES when buying groceries,
shop by weight or volume, be it by lb's, kg's, mg's, ml's, ltr's, ounces or otherwise, compare what you are buying to the alternatives, and where possible/prudent, choose the cheapest.
This tip alone can save you a shedload of money, and should be the rule for
every time you shop for groceries.