The key to good climbing-- that which brings the essentials of power and gearing together-- is to be relaxed. Put your hands on the tops, maybe scooch forward on the saddle a bit, and find that nice sustainable effort level. Relax your shoulders and upper body, and focus on driving the pedals.

Selecting gearing range is important to do before you hit the steeps. Anticipate which chainring you'll need and select it as you approach, using your cogs to manage gearing as you climb. It's possible to shift chainrings during the climb and may even be necessary at times, but in general is best to avoid as it offers opprtunities for shift problems and can mess up your rhythm.

Doing low RPM climbs can help build length strength, but it's important to match your cadence to both your power and stamina, meaning, mashing out a climb can really drain your leg strength, but if you can increase the cadence without blowing your cardio up, you'll find that you can top climbs without burning up your legs.