Re: How do you store leftover paint?
If I know I am going to paint again the next day I just leave the palette out and do a basic clean on the brushes.
If it's a long time between sessions then I put the palette into a covered plastic container in the bottom of the fridge. I don't freeze it.
PS. Love your avatar, in my house that's the first thing I open my eyes to in the morning!!
'Don't worry about your originality. You couldn't get rid of it even if you wanted to. It will stick with you and show up for better or for worse in spite of all you or anyone else can do.' - Robert Henri