Most people over grip and end with finger injuries. I do and had to unlearn it. Always take a second to find better position to place a protection. The key is how to distribute forces. You don't need to pull hard. You need to use legs more and use as little force on your fingers. Don't hang with all your energy. Relax and breathe.
Always warm up forearms and stretch your fingers before.
Crimps exert far more force on your fingers especially on pulleys and you can cause severe damage. Use open hand grips. You can climb with injured fingers as long as you use open hand grips. Use your thumb whenever you can and wrap it to support your index finger. You can tape or buddy tape your fingers. Buddy taping is to tape two or three fingers at once.
The key improvement into higher grades is how to use your legs more and develop different techniques with your feet. Quiet feet placements can help you focus. Slower foot placement will also give precise and better position.
From the point of hand injuries, it is important to use as little force on your fingers. It also makes you a better climber.