Before I ride, I do groundwork. (Longing with lots of direction changes, yielding hindquarters/forequarters, backing, desensitizing, etc.) I just like getting her attention and making sure she's focused on me, especially since I ride alone. If I notice that her mind is wandering, I keep it up until she's focused. Once under saddle, I always start with the same thing: circles in a closed pen. It's been hardwired into my brain from being a barrel racer for so long. I walk/trot/canter both directions, work on myself now that I've been riding english, then hit the trails as long as she's listening. When I say "trails," I really mean 200 acres of pastures, fields, and tanks. That's where we switch it up. Sometimes we go out there for a workout, sometimes we just walk and putz around. It all depends on the day and what I feel like doing, or if we need to work on something like shouldering exercises, leg yields, neck reining, etc. Sorry for the novel.
I just like being very cautious before I ride, considering we're out in "the sticks," plus I'm all alone with crappy cell service.