That depends on so much things, that it's impossible to say in general. Two things you shouldn't do: selling fridges in Greenland or selling snowboots in Brazil, even if you are a very good salesperson.
Things to take into account:
- your education
- your interests
- your experience
- your existing 'network'
- the local market now
- the outlook for the next 5 years
- the competitors
- the investment and the possible return on it
