Budget is obviously number one. I've not met many people who are able to earn an income while travelling. The formula that I most often see is a combination of (1) The most common - Working your butt off at home until you can bankroll it. (2) Shoestring what you have to make your trip go further (hostels, couchsurfing, eat smart, travel inexpensive countries, do volunteer work for accom/food) (3) Working holiday visa, quite a few people; for example travel South East Asia and then recharge their bank accounts in Australia and New Zealand, you need a visa for this however.
I've managed to earn an income on the road for the first time ever through Crypto Trading. I've been away since July now. The bear market doesn't help, but it's certainly possible. The blockchain has opened a lot of opportunities.
RE: I've Been Traveling For 11 Straight Months. AMA.