Congrats on getting a bike!

I have bad knees too and my advice there would be to shift down until you don't feel pressure on them. Many people ride in too hard a gear when they are starting out and it can be torture on the knees. It *seems* more efficient, but it is really hard on you.

The best thing that you can do IMO is train your body to be able to keep a consistent cadence at a reasonable fast rate, then downshift to maintain that. Push yourself, but not to the point of knee pain. Taking things slowly and steadily will allow you to gain strength without hurting yourself. Trust me, I just had to take a couple of days off riding because I pushed too hard and re-injured my knee.

As far as hands, the death grip is a natural reaction to fear but I think but it doesn't help you keep control of the bike. It took me overriding my body's instinct to grip the handlebars less tightly but it helps you have better control and you won't be nearly as sore. I think about it this way: the handlebars help you guide the bike, they don't keep you on it. Your body should be keeping itself upright, the hands shouldn't support you.

Keep at it and most of all have fun. I'm sure you'll have it all mastered in no time.

Anne