If I could have my GA charter days over again, I would only change one or two things. I would develop a 'Scan Action Flow' for each a/c that I flew, I sadly only learnt about these once I got into the Airline world. I always got the job done, but it was generally in a different pattern each time. ie, entering the runway: strobes on, tx on, pumps on. Next day it was pumps on, tx on then strobes on. etc
The second item would be to use a checklist, as a checklist after completing the scans.
My 2 cents,
go_soaring! instead