Just to add to all the great suggestions here...when you do try to stand, make sure you're not in too EASY a gear. If you are, your legs will just spin wildly and out of control. You need to be in a tough enough gear that you get some resistance in the pedals. Most people who do climb standing (part of the way), actually upshift 1-2 gears before standing to avoid this spinning out of control feeling. I learned to stand while coasting by shifting to a "harder" gear. Instant difference!

My favorite time to stand is to get a good burst of speed when leaving a stop sign or stoplight. It seems natural to stand then to get going.

Good luck!

Emily