Take Mark's advice the get some mechanic's training anyway you can. It really will help you calm down and gain more confidence whilst on the road.

Try to buy as NEW a bike as you can afford. Learn it well, take shorter trips to start off and do basic maintenance on the road. Build a good basic tool kit as you progress. Start doing maintenance at home with only your travel tools. All this will help.

There are good mechanics all over the world. The trick is to find the good ones. Hubb and other Online forums can help source qualified mechs. Ask for specific help for specific places before you get there. Keep notes.

But if you buy a simple, straightforward bike, then most basic maintenance can be done with minimal training and some decent tools. If your bike choice is good, problems should be very few beyond regular maintenance, tires, chain/sprockets, oil changes. More you learn the better.

Riding
If you are a "clumsy" rider ...that is not good You'll need to get better.
But how? Two ways:
Take up dirt bike riding ...take real dirt bike classes using SMALL bikes.
Forget the posers on the big BMW's ... little trail bike is what you want to learn on. YES ... these learned skills will cross over to ANY bike you ride.

Do track days on the race track or a good On Track rider training course. Some provide a bike, some you use your own. Huge value as skills builder.

Both these exercises will ramp up your learning curve quickly, your skills will improve 100%.

But riding a bike your general traffic sense and defensive driving skills need to be top notch too. Ask anyone who's ridden through India, Asia or parts of Latin America. INSANE drivers.

You need to be playing with a FULL DECK to survive those conditions. Do all you can to get better ... Don't wait and think you can "learn on the road".
Get in the training and practice NOW.