I want to save images and layer masks for use later. With my favourite images I want to be able to leave them over night, or longer, and edit them again another day. I find I get better results by doing that.
How can I save layer masks to allow me to do this?
You can save file as PSD and layer mask will be there tommmorow or any day in the feature when you re-open file. Beside layer mask you can also save channel (mask that is not attached to any particular layer) in the Window > Channels panel.