We only use half a dishwasher tablet (Lidl 2 in 1) too - we're in a soft water area and I'm sure it also helps stop the glasses clouding.
Don't use full measures of washing powder. Only use half a measure of fabric conditioner - and none at all if washing towels.
Re-use sandwich bags (either from the inside of cereal packets or I've used to get fruit or beg) for as long as I can.
Give ds chunks of cheese (wrapped in cling film - which can be re-used) cut from a larger piece for packed lunches.
To give ds his due, he's good at bringing back the empty sandwich bag and cling film.
Leave oven door open after use so that the residual heat warms the room (and the noisy fan turns off quicker)
Also use old envelopes for shopping lists - can also put vouchers etc in to them, so that you've got them easily accessible when you get to the till.
Have a "fat" jar, which I use sometimes instead of olive oil (eg when making shepherd's pie or frying onions), which is kept topped up from frying bacon or cooking anything else fatty.
Haven't bought kitchen bin liners in over 20 years - re-used other plastic bags. Even though I now use jute bags and/or "bags for life", we still seem to acquire enough plastic bags. On the couple of occasions I've run out, I've use a bread plastic bag for any "wet" waste. Most of oour food waste goes in to the compost caddies anyway.
Keep ginger in the freezer and grate it from frozen when required.
Use a plate instead of cling film to cover something that's being microwaved.