For cutting, I use a utility knife with replaceable blades and a straight edge. For curves, I use a small surgical scalpel. Works for me.

If you want really even stitches you'll have to use a star wheel tool. You just run the little wheel along the leather and it leaves little dimples showing you where to punch the holes. Nothing short of a machine will produce such even stitching. If yoiu're stitching along the edge of thicker (5+ ounce) leather, then use a groover first. That way your stitches are always the same distance from the edge and the threads end up below the surface level of the leather, so that they don't wear as quickly.

The Tandy company offers a beginners kit with these tools, awl, thread, and the book I mentioned in my earlier post. I think I remember that it cots about $30 when I got mine a few years back.