Having your rifle and scope setup properly to fit you personally is crucial to archive the best results on the range and in the field hunting.
Throughout the years I have come up with my own do-it-yourself processes to set up and mount my rifle scopes so that they fit me personally. The video below from the NSSF does an excellent job of explaining the process and how you can get the best results from your scope and rifle with no fancy tools needed.
The techniques used in the video have worked great for me. I liked his clever idea to get a scope level with the rifle.
And here is a great follow-up video from the NSSF that does the best job I have seen at explaining Minute of Angle (MOA) and adjusting your scope.