The trouble is that climbing hills is when you need to be clipped in the most.

First, have you learned to anticipate your shifts? You may be running out of gears earlier than you need to if you aren't pedaling smoothly all the way up the hill. Shift one gear at a time, use a cadence monitor and try to keep your cadence above 70 or so until you're in your lowest gear.

Learning to spin smoothly is part of it, too. If you're clipped in on one side and not the other, that guarantees that you're going to be working differently with one leg, which will put you off-balance. One-legged pedaling drills on flat roads or on the trainer will help with this, as will cadence drills such as pedaling as fast as you can in a low gear on a downhill.

Standing to climb will give you extra power, but it does use extra energy as well, so when you do it, make sure that you're either standing all the way until the next crest or false flat, or that you have a lower gear or two to shift into when you sit back down.

And ... most of us do occasionally run into a hill that we just. can't. ride. If it happens to you often in your area, and better shifting technique isn't helping, then you might want to look into lower gears. Cassettes aren't too expensive. But we also all need to know when our cadence is so low that we're in danger of tipping over, and unclip before that happens. If we have to walk, we walk. No biggie.