It took a while to plan, not just the trip stuff but finishing a job, packing up a house, signing cars off the road, cancelling bills etc.
We got a round the world flight ticket, we had to commit to the first six month flight times then half way through commit to the rest. It was possible to change for a fee. But we found the flights gave us a schedule to work around.
Some parts we planned extensively (you can't go to Tibet without being on a tour the whole time you are there, Machu Picchu books up months in advance, etc) other parts (Vietnam, Cambodia, Laos, Thailand) there is somewhat of an established back packer route you can follow and just make sure you get through in time for the next flight.
By far the least safe place was South America, we met many travellers there who had been mugged, beaten up, etc. It was our last destination and we were not very adventurous as we were tired and also just wanted to get to the end without an incident.
Other than that, we generally felt safe, there were one off isolated incidents (drunk Russian man on train trying to make advances on my partner when he thought I was asleep) which were uncomfortable, or going to a train station in Jaipur at 3 in the morning and waiting for a train, with lots of people loitering around and bothering us, and no real security or staff to reassure us, but these were exceptions rather than the norm.
We typically went to places which had a reasonable number of travellers, so it didn't feel too crazy in that sense.
