I cut plastic tubes (toothpaste, hand cream) in the middle and use the top half as a lid, as Phoebes describes. If I just cut the end off, I can't reach down to the other end to fish out all the remaining gunge. Well, toothpaste, I scrape it out with the toothbrush.
Shampoo, I have have very short hair and only use a bit the size of a pea to wash my hair. A medium-sized bottle lasts months and I can use good quality shampoo without breaking the bank.
As I have a dishwasher, which uses much less water than hand-washing, I try to save up the hand-washing and only do it every two or three days. I leave the water in the bowl to pre-rinse the next lot. (Not always the washing up water - [yuk] there is often water in the bowl from hand-washing throughout the day, too. )
Someone recently mentioned that those e-mails you get with loads of vouchers for various things really can save you money - I always delete them, but maybe I'll take the time to read them first. I noticed that there was a good underwear brand with a 20% offer recently - DH needs some new underpants!
I have never managed to plan my week's menus using the special offers from the supermarkets - I do make a plan and list and keep to it, getting most of my shopping from Aldi or Lidl, though, which means you don't get too distracted by snazzy items such as "luxury biscuits" or cakes, sweets, and their crisps aren't very good either - so that is a sort of saving, I suppose. Also saves calories!
I try and keep a check on foodstuffs nearing their use-by date, so I don't throw away too much.
I wish some things came in smaller packages - sometimes I have to throw out food that has gone off because I didn't manage to use it all up before it went mouldy or rancid.