On the open road in China, there is an unspoken law, the Jungle Law: "The bigger you can get, the better". As a taxi driver once put it: "The crocodile can pretty much do as he pleases, while the fish must be agile and swim quickly away". If a truck hits a guy on a scooter at full speed, the truck driver is pretty much walking away without a scratch. The largest thing on the road, can do whatever it wants to do. That is why you sometimes feel a little intimidated on a tiny scooter between a trailer and a tour bus going opposite directions.
In the city, there is a myriad of obstacles to look out for: Cars, buses, bikes, pedestrians standing around in the road and the million other scooters coming from every angle. There is actually a narrow, dedicated scooter lane next to the pavement in most city streets, although it's usually crowded. One thing you might want to look out for are the scooters and tuk-tuks coming right at you in your own lane. For some reason it's OK to drive in the wrong direction, as long as you keep to the side and have the blinker on. When possible, I suggest you stay in the middle car lane. This way you can pass slow bikes on the right, and you don't have to worry so much about front collisions from the left.
On the country road things are a bit different. It's still a good idea to keep to the side in the shoulder of the road. But here we run into another problem:
Large trucks are always loaded at two or often three times their capacity. This saves both time and money, you can't argue with that. On the other hand, it is one of the reasons for the "extreme drive-by", witnessed every few minutes. An overloaded truck can't actually stop or slow down behind a slower moving bus or other obstacle. It's too heavy! Their only option is to honk for a good ten seconds before impact and hold it while barreling past the slowpoke...
Smaller vehicles on the other side of the road have to anticipate this, and promptly get out of the way. This again causes a problem for scooters on the side of the road, who then has to watch out for the cars veering out in front of them. I can't tell you how many times we were sure an imminent front collision was happening right in front of our eyes. Every time, I slow down, try to get out of the way and prepeare for the worst. Somehow it always worked out in the end. Trucks barely get back in their lane before impact, and buses manage to slow down before an accident.
On slightly smaller roads, you should also keep your eyes open for potholes and bumps. I'm not talking about your side of the road, (Those should be avoided too, but this is for the advanced scooter driver...) what you really need to do is watch the other side. Approaching cars will definitively come right out in front of you to dodge even the smallest unevenness in the road. If they see you, they will honk first, so you'll know to stop or get further out to the side.
Don't be alarmed when buses and trucks honk as they pass right beside you. This is just a friendly reminder that they are coming up from behind and that you should not switch lanes right now. Although it often arrives a little late, it's really a nice sentiment. Maybe they have been there before, maybe they know your mirrors flop around, they used to be a small fish too. Before they got big.
Below is a photo of our scooter. The speedometer didn't work at all but at least the fuel gauge seemed OK. When we first got it, the mirrors dangled lazily down the sides, flapping in the breeze. With a little sports tape, they worked better.
On a more serious note: I am exaggerating, keep it cool and you'll be just fine. Oh yeah, and scooters can legally run red lights, nobody will stop you. But you know, you probably shouldn't.
From a bar in Xi'an, China. Scooter safely left behind in Yangshou.