Join Date: Nov 2010
Location: north central Illinois
If your hands or forearms hurt, you need to relax your grip a bit. You may have to concentrate on it now, but it'll become second nature as you get more comfortable with the bike.
One little tip about throttle wrist position...start with, and keep your knuckles higher than your wrist. If you grab the throttle with your wrist high and your knuckles wrapped around the front of the grip, you'll get the effect you encountered at your first stop sign, which is that your palm rolled on to the throttle as you grabbed for the brake. If your knuckles start on top of the grip, with your wrist a little low on the back side of the grip, see what happens when you reach for the brake lever. Your hand should move forward and effectively close the throttle as you reach for the brake lever.
Any fool can jump on a bike and ride real fast in a straight line. The real skill is in learning how to stop quickly and safely, and performing low speed (parking-lot) maneuvers. Practice using the friction zone and counterbalancing while making tight figure-8's. (I still do this regularly) Don't panic if you scrape the floor boards as that scrape is actually a good sign. It means that you trust yourself and the bike, and shows you the lean angle limit.
Stay at your own pace and don't let anyone else pressure you into riding outside your comfort level. Most of all, enjoy the ride!