Ok, I want to plan a road route (cough) and need to know how to indicate how to go left/right at key road junctions. I am using a Garmin 305, so do I just mark waypoints as key junctions (I think it's limited to 100 waypoints). However, this is then just going to give me a set of waypoints connected by straight lines, so road distances will be wrong.
use bikeroutetoaster instead. Not sure about the 305, but in the 705 you use coursepoints instead of waypoints and you can use loads more.
Bikeroutetoaster will autoroute for you as well keeping you on the road and your mileage accurate.
use bikely.com as is will auto follow roads which makes planning a road ride very quick and easy. You can then export it as a gpx file and upload it to memorymap. You shouldn't need to mark junctions that are a significant change of direction as the garmin will pick that up and tell you automatically. For smaller direction changes eg a fork in the road, you can just put a waypoint in.
Cheers guys, used bikeroutetoaster, all seems ok, will find out tomorrow!