OK so I don't know if this will work for everyone, but I find this teeny tiny little tip helps me make the washing up liquid go further whilst also washing things more effectively - less scrubbing required.
It is simply this: dilute your washing up liquid with white vinegar. You could also use lemon juice for this, it would smell better, but I can get cheaper white vinegar than lemon juice so I use that. I use an old washing up liquid dispenser, and in it I mix about one part vinegar to two parts washing up liquid. If you have sensitive skin, this may not be great for your hands, but it really cuts through grease a lot more easily, and one tiny dribble (it is now pouring rather than squeezing consistency) is enough for the nastiest pots and pans.
I have pondered making my own out of castile soap at some point, but am still struggling to identify a local source of castile soap. And how would a few drops of essential oil go with the mix, do you think?