Walking the GR10
1. Planning

After deciding to walk the GR10 the first thing I bought was a decent guide. By far the best is the set of four guides published by the FFRP (Fédération Française de la Randonnée Pédestre) which contain detailed maps (extracts from the IGN 1:50000 series), estimated times, places to stay plus a section showing the climbs and descents for each stage. Indeed, if you were to walk the GR10 without any diversions this guide would be the only thing you would need, provided you can read French. The cost in 2002 was 13.72 Euros per guide.

As I was occassionally deviating off route and because I like maps I also invested in a selection of walking maps. For the lower level areas and where I was staying on the GR10 I used the IGN (Institut Géographiqye National) 1:50000 series which cover the whole of the Pyrenees in 10 maps. For the trickier stuff I bought some IGN "Top 25" 1:25000 maps. This latter series have the advantage of being GPS compatible whilst, for some reason, the 1:50000 aren't. These maps cost about 10 and 9 Euros respectively.
One of the four
FFRP guides to the GR10
The IGN 1:50000
"Pyrénées" map series
The IGN 1:25000
"Top 25" map series

Things to consider when planning the trip include which way to go (east-west or west-east), whether to do the walk in one go or in stages and when to go. I went east-west because that's the way the guide is written and it is easier to read it forwards than backwards! Also, it means that the first climb of the day (and there is usually a climb to greet you in the morning) is made in the shade so you can remain cool and fresh. I chose to walk the GR10 in stages but, there again, I had the fortune to be living near Toulouse and, thus, be able to get to the start and end of stages in a few hours. I tended to walk about one week a month depending on other commitments which allowed both by body to recover and my mind to forget. Judging from fellow walkers, tackling the entire walk in one stage requires a lot of physical and mental stamina. I started the walk in April and finished in October though I has to carefully plan the first three stages to minimise walking on snow.

I found the guide and 1:50000 map excellent when planning each week; I used the map to give me an overall view and the guide to identify rough times and potential nightstops. As I was travelling in and out after each stage I had to choose suitable towns in which to start and end. As I didn't particularly want to carry a tent finding suitable stages was not always easy and on several occasions I had to walk "double étapes" - ie double what the guide recommended. In reality I found the times indicated by the guide very generous and normally I could reduce them by up to a third. However, off the GR10 the times where much closer to my actuals.

Finally, I found some excellent Internet sites to help with my planning - both official sites from various walking or regional bodies and unofficial sites of people who have walked the paths previously. For example, I did not have a guide to the HRP so I used a site to estimate walking times, not always successfully!