I had a hard climb up that learning curve. I too had a bit move on me the first time, just as I was getting near to finishing. I keep that first attempt hanging on the wall as a reminder.

Take your time, check and recheck as you go!

Make lots of sawdust and scrap wood. You will quickly learn as to what works well and what doesn't. I try to rotate the piece in only the one direction and move the cutter pushing 'against the cut'. This helps eliminate back lash and to compensate for the deflection in my low end rig.

Every time that you do one, it will be a little bit better.