whenever i'm just having a mix I'll hit the record button. Might get something done worth sticking up, might not. I'm not one for putting in a lot of planning when I try to record a mix. I'll go through tracks to see what I want to use then use a selection of those. If I mess it up and wouldn't keep going through it. I'd just do something different but that's only because trying to mix the same tracks in the same order over and over bores me. so just practice as much as you can, record everything you do and have fun with it.