Different people have different goals for worldwide hitchhiking. Some questions to consider:
Some parts of the world, like North America or Europe, are densely populated and make for easy hitching. Other parts, like Central Asia, have lower traffic and may result in harder transportation.
Crossing the Pacific or Atlantic Oceans present some difficulty. This can easily be overcome with a little grit and determination. Hundreds of sailing boats cross the oceans every year. Waiting in busy ports like Grenada, Madeira or Panama can help. Talk to boat owners, be friendly, helpful, and approachable. Something may turn up. The internet is also a useful resource, there are many websites that match crew with short-handed skippers. They might just be going the right way.