1. Eventually all bikes will breakdown if not maintained. Make sure you know how to repair all mechanical parts on your bike. I couldn't repair a disk brake, and wouldn't you know, that was the thing that went wrong. Try to keep up to date with some sort of token maintenance schedule.
2. Take the lightest and smallest packing equipment you can afford. If you have 4 panniers, a bar bag and a top bag, that you have to pack and repack every day and to then have to propel the extra weight up hill and down dale, you soon get to resent the extra burden.
3. Don't worry about getting an expedition touring bike. They are mostly over priced and overweight and no more reliable than any other bike (maybe wheels and pannier racks excepted, but you can upgrade when things break). Just make sure you are comfortable riding your bike for long periods. Use Shimano gears and brakes, these are the most widely available.
4. Route. Biggest problem we've had is frustration at not actually being able to cycle continuously around the world. Instead it feels like we've ended up hopping around to a pre-ordained time limited schedule that we whipped up over a couple of beers in the pub. If we were going to do this again we both agree that we would just set off from home and see where we got to. Cheaper and you don't face the constant pressure to get somewhere different to where you are right now.
5. Take a cheap and light laptop with you and install Skype on it. Yes it's extra weight, but to compensate you can dispense with a couple of guidebooks as a result. To give that some sort of context, the Lonely Planet India book weighs nearly a kilo. You can phone your family and friends for hardly anything and over a year you'll save enough money on internet cafes to pay for the thing. Wifi is everywhere these days and it makes communicating and looking up info soooo easy. We bought one in Aus and I don't think either of us have regretted it. The only downside is that laptops are a bit of a target for thieving tea leafs.
