I find that no change in mood is necessary. When you're with someone who wants you, they are always game. Sometimes when I'm driving with my wife, I'll reach over and tweak her nipple to get a giggle out of her. The other night we were watching TV. Our son was upstairs sleeping. The show we were watching was over and she was about to go upstairs to bed. So I said, "Hold on a sec..." and crawled over to her side of the couch and started kissing her. I stroked her neck a bit, ran my fingers through her hair, then let my hands wander. Before you know it, her clothes are coming off, as are mine. We had some fun in the living room then ran upstairs to have more fun in the bedroom.
This is by no means a routine. It's different every time. There's just no elaborate preparation. Chemistry between two people means you don't have to trick each other into sex with some subtle ploys.
As for after, sometimes we use towels, but usually we clean ourselves up in the bathroom. She tends to go first since the majority of the mess is on her when we're done.