Separating plastic, saves about 2/3 of trash at this household.
It's funny you should say that... here in South Africa there is no official re-cycling requirement, so all the rubbish goes in the same big wheelie. BUT there are hundreds of folk who make a living of separating plastic and cardboard from the main rubbish and I assume they sell it on to the waste companies. So we keep a large bin bag going during the week and all our 2l plastic Coke bottles, bread spread tubs etc all go in there. And yep, the one or two bags we put out with the plastic are often bigger in bulk than what's in the wheelie.
I'll start adding my cable-tie offcuts to that bag