There is a seperate transfer forum available to ask the question on Transfer to another service.
It's not a problem if you want to ask it here as the National Guard typically takes in various services backgrounds and the experience level on this board might be higher concerning the National Guard. I just noticed that it is being asked over and over again on this forum.
I served 8.5 years in active duty Navy. Then 5 years in the Air Force Reserves. Then 5 years in the Army reserves. Then 8 years in the Navy reserves. Then retired with 20 good years.