There are many options for navigation. Paper maps are touted as the pure way to go, GPS units are common. We have gone for using apps on our phones and we are very happy.
The apps can eat the battery but we can charge with the battery pack if needed and typically we just use the phone to check we are on the right road, check the distance to the next turn and then switch it off. The bike computer tells us our distance travelled and therefore when to switch the phone back on.
I do like the idea of paper and a compass but there is enough other challenges we face and I also think we get the most from the country by using the app to choose the best routes. For example we often see a nature reserve/river/waterfall/hotel/temple on the map and divert.
We primarily use OSMplus on the HTC phone. The app was around £2 and the maps are open source. You download country by country and store on the inserted micro 64GB SD card. The files are big and Wikipedia entries, contour lines and hill shading are downloaded separately as big files.
The app does route planning, and will do spoken navigation but we tend to pick our own roads. Lately I have been exporting a planned route and trying to upload it to an app called GPS visualiser to see elevation/distance plots like in the ‘tour de france’. Having a profile of your next 7-10 days is really handy for planning when and how you will tackle those climbs.
We back this up with MotionX-GPS app for the iPhone. It uses the same map source but we’re limited by storage on the phone and it has slightly less functionality. I’ve been looking for better iPhone apps but the storage problem really restricts things.
Quite often we find the maps will not include some roads but there have also been times when it turns up some gems. It is an open source project (Open Street Map) and relies on user input so if there are unvisited areas it can be weak. I do plan to track our route and upload it when we go ‘where there are no roads.’
We also use Google Maps, especially satellite view to check potential camping spots sometimes and get a feel for the countryside. But that needs data which we usually don’t have.
Finally we do try to carry a paper map for the country we are in. It has been most useful for showing people where we’ve been! It’s nice to be able to swap maps with cycle tourers going the other way when we can. We carry a compass just in case too but have never needed to use it.