Don't bother looking for a travel buddy. It's more trouble than its worth for the companionship. If you're social enough, you would make enough friends and fellow travellers along the way. If you're not, learn!
Central Asia is the trickiest part and you would need to plan your route in advance, due to visa issues and certain borders being uncrossable. It's a large area, so you would have to eliminate some countries if you want to stick to pure overland travelling without significant backtracking. Caravanistan.com is a good place to start your research.
The cheapest/easiest way to obtain a visa for Azerbaijan is from its embassy in Tbilisi, Georgia. Processing time is 5 working days, so factor this into consideration for your trip. Personally, the experience there wasn't worth the effort and high visa fees to get in, but you might enjoy it. Might as well do it if you're going to be in the region anyway.
Iraqi and Syrian tourist visas are close to impossible to obtain now, even if you have the balls to visit them. Transit visa(6 days) is still possible for Afghanistan, if you are willing to bear the high visa cost and paperwork.
Other than the above-mentioned, everywhere else(the Asian and Eastern European leg) is easy and relatively fuss-free to travel in. One last thing..be prepared to go for more than a year; you will likely change your mind about the duration once you begin.