I did the walk from St Jean to Santiago in Sep 2007, 4 weeks and 3 days of walking. Mostly as a single female, although I did start it with a friend but she walked too fast in the heat for me. Beautiful experience.
Main lessons learnt were - abandon a lot of the Aussie bushwalking principles of carrying items just in case - that's what they provide shops in the numerous villages, towns, cities for. Also the Aussie down sleeping bags - too bulky & hot for your large day pack. I shipped mine, and other bulky gear carried just in case (eg fleecejacket) to the poste restante in Santiago to collect at the end. Bought a very small compact sleeping bag for approx E40, which was brilliant for sleeping in the albergues (walking hostels) and has proved very useful for Australia & NZ walking. Have not seen them here in Australia yet. In an Australian winter, I sleep with thermals & cope fine.
10kgs in a large day pack (35litres), with a proper harness system is about all you need. Two sets of clothes are all you need - clothes washing gets to be high on your daily agenda each afternoon.
Blisters - something I haven't seen in many years of extensive Aussie bushwalking on the mainland & in Tassie. The Germans provided the following tips - lather your feet with cream every day before you put socks & boots on. I ended up with severe blisters after 3 days with walked in boots (two-three layers deep - photos available if you are keen). Yet I have walked for 10 days with 20kgs here in Australia. I stayed at a albergue where it is claimed that there are magical healing powers for blisters in the waters there. Let me tell you, they are magical. I spent the afternoon there soaking & sunning & they were almost gone the next morning. Miracle heh.... I then creamed my feet, wrapped my feet completely in bandages, put on socks & did the rest of the walk in my Teva sandals http://www.teva.com/productdetails.aspx?g=w&productID=4173&model=Dozer%20III
. These sandals got an awful lot of comments, as everyone else was in boots. I'm a converted Teva sandal walker now for day walks & summer at home.
Walking poles are big in Europe, but there's only a few places where they would be useful, unless you have an injury & rely on them. Watch out for the bicyclists who use the same route without bells.
The albergues in the eastern end of Spain have a ritual of 10pm for lights off & 6am for lights on. Bang! I suspect the circuit breaker does this using a timer, as there's certainly no person switching them on & off. Head torch is essential to cope with this. Again I found very small head torches in Spain ( 4 years ago now), that I haven't yet seen in Australia. I lost my Aussie one....but now have a very small, light in weight, bright, multi-mode. Red light is useful on your torch to use without waking others.
Happy to share other experiences if you wish.