Yekrut nailed most of what I have learned as well over the years.

NEVER underestimate where a committed gobbler may show up. I made this rookie mistake last year and it cost me a good gobbler (no comment hellfighter). He may gobble at 9 oclock one minute and then pop up at 5 oclock 5 minutes later. He makes his living doing this. If he is close, have your gun up and ready. I had mine shouldered and on my knee and still couldn't get it presented correctly when he popped up 10 yds at 1 oclock on me when he had just gobbled at my 7 oclock not a few minutes earlier.

In the offseason, learn to shoot from your opposite shoulder. It helps with the above.

Learn to use calls that other hunters do not use or know how to use. Wingbones, tubes, etc.

On pressured birds, less is more. Tone it down a bit, maybe to just a single cluck or purr. Listen around you. If the real hens are not sounding off, you sounding off just lets them know you are not a local hen.

A turkey "call" can be anything; a scratch in the leaves, a slight rub of a turkey wing on a nearby bush, the beating of a turkey wing against the air.

I'll add as I think of more.