If you want to become more careful then you have to:

1. Age: the older you get, the more errors you have made in the past, the more careful you are.

2. Meanwhile... make yourself a procedure with bullets (or a decision tree) for critical things and stick to it . Sticking to it is fundamental. Something like "1. Make a backup of the original work. 2. Check the origin of the problem. 2. Check the solution done. 3..."