Many times, I'm not very conscious when I begin creating, because the moment of creations has come as a sudden opportunity, rather than an intentional carving-out-of-time. What this means is that I often don't know why or what I'm making what I'm making but I know I simply must generate something.
But if none of that is there, I just start somewhere. Perhaps in frustration I'll scribble on my sketchbook page and make some marks, just to warm myself up. Maybe I'll stare at the wall for a bit, or spend a few minutes mind-mapping or journaling. A theme or task may come to me then. It's a lot like knocking on the door of someone who's really busy and intent on ignoring you.
On some days, the obstacles are very concrete. Perhaps I'm worried about some household thing, or an appointment later in the day, or I've run into a roadblock with some client work that feels more urgent (even though I'm ahead of schedule). Often I try to tackle small things when I feel distracted, hoping to shed the distractions as the real Work comes into place.
And when I'm there, I drift. Sometimes in silence, sometimes with music. Sometimes I'm listening to a podcast if I feel as though I have true direction and can have the background humming.
But mostly, I think about what I've done before, what I want to say, and new ways I can say it. Or I just disappear into the joy of making, solving technical problems, and challenging myself to stretch a little further, to try something just a little different, and to let go of what I think it should be.
All that to say, it's less thinking about making, and more like entering within making.