There are quite a few options. All I would add is that you are patient and experiment a lot with it. There are a couple of ways of defining routes, waypoints, ways of mapping etc and it can have a massive impact on your experience

For example, where a road is a dual carriageway or has as solid barrier down the middle, failing to zoom in and ensuring your waypoint is on the correct side of the road will have you doing u-turns all day long.

Also, this kind of routing overrides any of the intelligence built in to the better, more current GPS units. For example avoiding gravel roads and interstates.

As a rule of thumb, when I am touring and have to pass through larger cities / towns I let the satnav do its own thing through the city to a waypoint at a known point the other side of the city and then carry on my journey

Not rocket science, just patience and understanding the technology

 

My experience of both Garmin and TomTom is that it takes a lot of time and patience to master the darned things and there seems to be no quick fix. Just try to spend less time planning than riding!

 

I have a Zumo 550 and have used both the Garmin software and Mapquest's "send to GPS" function. In both cases, what is sent to your GPS is a series of waypoints, not the actual route. Your GPS will still calculate what it considers the best route between those waypoints based on your preferences. This may or may not be the exact roads you picked on the software map.

 

You might want to take another look at Garmin's Mapsource software. If you plan a custom route in "shortest distance" mode it will download to the Zumo 550 exactly as you routed it. I do it all the time.