Street Riding in the Rain
Riding in the rain can be very un-nerving to say the least. There are several things you need to consider that are very different than what you're used to while riding on dry pavement. Among them are traction, visibility, and of course, cars behind you.
If you MUST ride in the rain, you will need to slow down and pay extra attention to your surroundings. You will need to be more aware of paint, man-hole covers, "road icing" R/R tracks, and oil (it floats). Motorcycles tires do well in wet conditions, better than you might think.
The key is to be smooth and steady. Any quick movements or adjustments will upset traction and stability. You don't want to twist the throttle quickly, turn quickly, or brake hard, especially while leaning over. Determine your speed ahead of time, and leave extra room for you and any cars around you.
You will also want the proper gear. Normal riding gear won't cut it. You'll end up wet and cold, and that makes for a very nasty ride. You need to stay dry, and that means a water-proof jacket and pants, boots, gloves and a full face helmet. You may need to treat the inside of the visor for fog, or leave it slightly open to eliminate the fogging.