Minimize the holes that you cut, and make sure that your pop rivets are stainless steel and of sufficient diameter. I failed to fully heed this warning with my first mast, and I've never been able to match the speed I had before it broke. This takes a little time in beginning, but will save time in the long run. The key question you will face is whether to run your halyards and controls internally or externally. I chose to go outside with everything on my second mast because it takes a lot less time, its easier to inspect the lines and you end up with far fewer holes in your mast section.
Many people go internal because it reduces windage and looks much better.
Most people do not put the spinnaker halyard internal, however, as this requires a hole in the unsupported upper section of the spar. DM-1 mast section. I ordered with a group through Mike Parramore, as he gets a dealer discount. You can check with Greg Koski about this as well. I don't have it handy, but its on the web.