Get strong! How?
The best way to get strong for climbing in general terms is to go climbing, most of us don't have that luxury. Climbing is also a bit tweaky on certain muscles. I myself have always had trouble with my fingers in the crimped position, and been injured many times! So some safe, or easy to regulate controlled stuff, instead of pulling on a tiny crimp in a dangerous position might be in order. Or thinking about things to maximise your training in a short time might help. As Wolfgang Gullich said, the biggest muscle is your brain!
This is a very old school ,very, very calibrated spring loaded device that can be used to train, or measure your strength. It's used just for grip strength which you might call hand strength but here I am using it to isolate my fingers and isolate them in a crimp position.
This is what I used to do at school, and believe it or not, this worked a treat, my crimp was never as strong as when I was a kid. Never was lighter, than when I was a kid either! I would simply make the crimp position, and crimp it a bit harder, with or without the thumb. "Bored at school" was a real risk, this simple position helped keep dreams alive.
Finger boards have really made the weekend warriors job a bit easier. Get one, wear one out, you will get strong.
Any ring work will make you strong, just hanging off them when you are fat and out of shape will get you strong. The pair of rings (above photo) are extra thick, they were extra strong because I used to use extra charge, I still love them, Ice climbers should all have a pair of thick rings! But everybody needs these! Rings also spin which means your elbow tendons don't get stuck in that horrible place that can cause chronic pain.
Unbalanced dumb bells are real fun, so is having broken toes, never train with out shoes!
Palm facing you, there is a fancy word you can use if you want for this movement. You should also do pull ups or machine pull downs, with your palms facing you and with palms facing away. Mix it up.
|Palms facing away.|
Try a few of these, why don't you?