I've only been riding for 2 years but learnt a lot in that short time:

Incident 1: Within the first few weeks on owning a bike, I was on a straight road near the Ridgeway in Swindon. I wondered if I'd be able to shimmy back on my seat onto the pillion seat and still be able to steer. I struggled to maintain control over the steering and nearly rode into a ditch.
Lesson learnt: Don't be stupid.

Incident 2: This has happened a couple of times. In the right hand lane on a dual carriageway and a vehicle in front (usually a van or lorry) pulls into my lane without looking, almost taking me out.
[Lesson learnt:[/] Be wary of sudden maneuvers, car drivers probably not have seen you.

Incident 3: Riding along in the rain and went around a large roundabout (the one by Windmill Hill in Swindon) at my usual speed. The back wheel started to drift out and I almost shat my pants. Thankfully i loosened off the throttle and maintained control.
Lesson learnt: Ride to the conditions.

Incident 4: Riding along in the pouring rain (a badly timed outing!) and hit a massive pothole that had been filled with rainwater, making it practically invisible.
Lesson learnt: Pay attention to the road surfaces, especially in bad weather. Look out for large puddles, potholes and slippery surfaces such as manhole covers and paint.


Incident 5: Has happened a couple of times; Riding at night, and an animal (such as a rabbit) runs out into the road in front of you (managed not to hit any yet!)
Lesson learnt: Animals are unpredictable. Pay extra attention at night and manage your speed so that you can stop suddenly if need be.

Of course, there are other things that you learn along the way, such as to be extra careful whilst filtering and whatnot. Recently, I've learnt to pull the clutch in and idle past whilst riding near any police, as my exhaust is a little bit loud...