We all do things differently and it can take a while to find something that works when you start this carrying gig. I know it took a while for it all to "click" for me. One of the things I found super helpful was asking around to see how everyone else dealt with things like how they marked parcels and how they held the mail, etc.
Marking parcels can be a real pain when you are on a route you don't know. Would you please share the way you handle this? Do you write them all down or flip letters, toss in a maker card in the case where it goes or at the start of a swing... you get the idea.