First thing we did is buy the biggest, most detailed, Mexico, Central, and South America maps we could find. We had them laminated, then dedicated a wall in our home office to trip planning. Using color coded stickers, we began to mark all the cities where we had friends, and all the sites we wanted to see along the way. Doing this alone, just about traces a route for you; simply connect the dots.
The rest of the route planning has involved talking to a lot of our friends and contacts that have done similar rides in the past. Our friends Hank and Alfonso who have ridden extensively in Mexico and Central America, gave us great tips on which roads to take, and which border crossings to avoid. Our friend Dan sat down with us one night in his map room and traced out all the roads he's ridden during several trips to South America in the last few years.
Brayde purchased several helpful guidebooks including The Adventure Rider's Handbook, and the Central America Handbook and South America Handbook by Footprints. The Footprints handbooks have been very helpful. They go into more detail than you can imagine, have a variety of city, region, AMD country maps, and even go as far as to tell you which documents you need for each of the border crossings. We highly recommend these books.
At this point, I think we've put together all the pieces of the puzzle and a rough route has taken shape. This is by no means a set plan, and I'm sure we'll deviate from the route often as we find new things to explore. Having a rough idea of where we're going will be helpful in planning mileage, budget, bike maintenance, and other important details of the trip.