yes absolutely check the contents of the fridge and freezer before you write the list.
also, make double of stuff like, pasta sauce, chilli, shepherds pie, and bung in the freezer. Will make a meal up for the following week too.
buy 2 or 3 loaves of bread and freeze for the week.
big packs of crumpets, potatoe cakes etc..in the freezer for breckies.
Buy shops own, not expensive brands.
Washing powder, i buy the little blocks, 2 in a pack, i use one block per wash load, get 24 washes out of a box instead of 12, use the ones with the conditioner in.
clothes are perfectly clean and still smell nice.
use up cupboard contents so shampoos etc lurking in the bathroom cupbourd, cleaning products, make sure i use them up completely before buying new.
it takes effort, but saves a fortune.