The specific tools you use for sketching are a matter of personal preference. The goal is to choose tools that are intuitive to you, tools that don’t place a technical barrier between your thinking and your sketching. Don’t use the computer for exploratory sketching. Even with a responsive pen pad, there is currently too much of an interface barrier between your head, your hand, and the digital image that results. Focusing on pressure settings and keystroke shortcuts interferes with the kind of spatial, intuitive thinking that exploratory sketching seeks to promote.