any advice on those stubborn hills?
Don't look up. Never. Only see the 2-3 meters of road in front of your wheel. It's less intimidating and suddenly you see the end coming.
This is the only quote from Lance I care for.

You don't stand on a sustained climb because it wears you out too quickly, as you'll tend to be 1-2 gears higher up and your HR goes up thru the roof.
But you can power up a little roller without losing momentum. Or power up over the crown of a hill if you know you'll get some rest right after.
But it helps now and then to give your back, and your leg muscles some relief (different usage) on a sustained climb.

You'll do 20 miles of gigantic mtns soon. then 40 - 60 - no one's gonna stop you

another lesson: don't cross-chain. i.e. don't use your leftmost ring in front with your rightmost sprocket in back. Pretty easy once you learn to look down. Reason: it's easier on the equipment. (On a double crankset I don't *really* care)