I agree with the uniformity statement. One of the things I have done is use a carpenters slide rule/square. I tapper the nock end, then I can measure and mark each line on the shafts using a very fine light pencil. I find it truly help get them uniform. There are other methods, but this one works for me.
As for your cresting you did a fine job. here is a pic of one of my first attempts. Good fine brushes will help make the line much neater. I was quite proud of these at the time, even though the lines are uneven and they really were quite ugly. I had nobody around to ask question to, so it was trial and error. The more you do the better you'll get.
It all just a matter of time and a steady hand. After a while it becomes more of a chore to figure out what they should look like.