Check your work. “Check your work” is something you’ve heard since your math teachers in school. It’s good advice in the field and good advice for our exams, too.
Example: If you are going to make a significant system change that can impact the boot process, maybe you’d better reboot the virtual machine on which you are making the change to ensure that it actually works. Do you know how we score a system that comes up in a su-login shell? Answer: with a big, fat zero.
Don’t let us be the ones who discover you have rendered your system unbootable. Check your work, discover the problem yourself and fix it. Allocate enough time to check your work. Decide on a time when you will stop actively working and start checking. If you get through your checks successfully, you can go back to working on the tasks you hadn’t completed when you started checking. Then make sure to check again because the change that you just made might be the one that leaves a critical VM unhappy.