The Great Outdoor Challenge was conceived in the late 1970s and has run every May since 1980.
The concept is simple – design a route that you walk, self-supported, from the West coast of Scotland to the East.
How to approach the planning? Well, research what others have done before! Some have made several trips, and many have recorded details of their routes and their equipment. This is a list of my blog accounts from my first trip during the famous 2012 hurricane. Here is the TGOC website.
Many like to incorporate the Scottish mountains in their TGO route. Here is a good source book.
There are other Scotland backpacking trips described here. Ideal training for the TGOC. See here for a trip around Dalwhinnie, for example!