Irulan said it very well! I would just add a bit more. When you are going for slow and steady, that means starting out slower than you think you need to. SO many people start out like a crazy person at the bottom of the hill, thinking to get as far up as they can and then crash and burn before they hit the top. (I am exaggerating a bit here.......)
When you know a hill is approaching, take two-three deeps breaths right at the base so you at least start the hill withough being out of breath. Helps with focus, also. If you've got momentum from a downhill, use that till you start to slow down then start pedaling and go ahead and shift down into an easier gear. Think about wanting to keep the same cadence for the entire hill. (You can't always do it, but its a good thing to aim for.) Generally, you need to shift a couple seconds before you think you need to. That way, you don't tire your legs out quite as much. Hopefully, you can keep a decent spin all the way up. I usually don't start up the hills first, but I often am the first one up. I pass people on the way up that started out too hard and then can't keep it up.
Of course, the best way to improve at hills is to ride them. Lots! Practice your technique, focus on what you're doing, think about spinning your pedals, eventually, it gets easier. It NEVER gets easy. Cause once it does, then you end up trying to go faster so its always a challenge. But we like challenges, don't we?
annie
Time is a companion that goes with us on a journey. It reminds us to cherish each moment, because it will never come again. What we leave behind is not as important as how we have lived." Captain Jean Luc Picard