Before you rent — the boring part that matters
Check your travel insurance covers a motorbike, and at what engine size. Most policies exclude it entirely, or cover it only with the correct licence category — and a great many people ride without either and find out afterwards.
Many countries require an International Driving Permit with the motorcycle category endorsed. A car licence from home is frequently not enough, and it is the thing that voids a claim.
Photograph the scooter from every angle before you ride away, including existing scratches, and film the fuel gauge. Damage disputes on return are common and a timestamped photo ends them.
Wear the helmet
Every time, including the five-minute ride to dinner. The overwhelming majority of serious injuries happen on short trips at low speed, and roads are gravel, sand and dog more often than they are tarmac.
If the rental helmet is broken, ask for another one. They always have another one.
What it costs
Typically a few dollars a day for a small automatic, less by the week, plus fuel which is sold in bottles at the roadside on most islands. Expect to leave a deposit; try to avoid leaving your actual passport, and offer a copy plus cash instead.
The roads worth the whole day
Inland roads past rice fields and grazing buffalo, where the traffic disappears within ten minutes of leaving the coast. This is where the day stops being transport and starts being the point.
Coastal roads in the late afternoon, heading in whichever direction the sun is not. Ride out for an hour, stop wherever looks good, and come back in the dark only if the road is lit — which it usually is not.