First to safety.
Knowing well the machine.
Learning to correctly measure .. (So do not waste time and do it again).
Learn about their hardness materials and how they should be machined (eg cutting speed)
Right tools for every job.
With redoubled attention wood, a material that can easily cause accidents.
Never never! find that you are already an expert, the experience tends to to leave us relaxed and there lies the danger.
Finally take it easy and analyze all the variants (Plan the process)