Not that much to it... for small pieces, I use a relatively dull 1" chisel. Hit it with a hammer to start the split, then when I run into the handle, pull it out and replace it with a wood wedge, and hammer that on through.
For big pieces, saw a slot 1" or so deep to get it started, and then hammer the wedge in.
One thing to keep in mind is that you should always split into two equal size pieces when possible. Splitting a thin brace off the edge of a larger billet usually doesn't follow the grain, due to the thin piece bending outward and stressing itself. If both pieces are equal size, they bend equally, and the split follows the grain.
Then make lots of plane shavings to get the pieces squared up and sized
A hatchet would probably work OK too, but I don't have one.