I keep myself in shape--gotta be healthy enough to stay alert this long, I also make certain that my bike is in top running order or have any overdue maintenance taken care of before the ride, I watch the weather from several points along the ride, and I preplan the route.How do you prepare?
When I plan the route, I look for gas stations that will be open, or at least have 24/7 automatic pumps. As proving that you rode the route taken, the IBA principally relies on dated, timed receipts which also show the address. The receipts should also be in locations on your route which show that you didn't take any short cuts--get proof in the "corners" for a route that isn't a straight line. I have used paper maps or even just notes about where to stop for gas before. This time I used a Beeline navigator and put my 12 planned stops into its memory so it was all there while I rode. I usually try to avoid big cities due to traffic, but here I knew that Chicago would be quick because I'd be getting there fairly late at night.
The weather can vary greatly on such a long ride, so I plan for layers that can be removed or added and luggage to carry any extra stuff. I brought both my warm and cold weather gloves on this trip, and used both. Rainproof gear or a rain suit are also helpful.
I also carry some small tools to deal with little problems, haven't really had any, and I always carry a tire plug kit. I also have the power port on Ninjette Noire, and used it to keep my phone topped off. And I linked my phone's location to my wife's phone through our Google accounts so she could be reassured that I was still moving and not in a ditch somewhere.
Keeping your health up is important. Dehydration is a threat even if the temps are reasonable. Light snacks and regular water or pop will keep you going. Any sign of tiredness can indicate a need for water or food. Plan to stop and get a room rather than get groggy and crash. I figure that I can always try again.