If time allows it, I would recommend cruising on as many boats as you can (even ones that aren't within your budget!). websites like findacrew.net were a good start for me to get a ride.
You will learn so much about what works and what doesn't work for you, what you can live with and without - I started doing that and ended up sailing over 8,000 Nautical miles on other people's boats before buying my own - my boat ended up being totally different to what my initial picture of what i wanted/needed was.
In terms of RTW sailing, the most valuable piece of advice that was given to me was buy a mass produced production boat - reason being that they generally have common components that are easier to find parts for in remote places. They are also generally speaking easier to sell in remote places should you find yourself in a position where you need to do that.
the setup that worked for us is documented here Cruising Yacht for sale
- unfortunately it's time to sell my floating home.
Good luck and go for it, you won't regret it!!