For Linesmen only, and those who want to be like us.....

[Jim D]

Also unless there is a yard or less to work with - in other words, the ball is at the 39 1/2 (and let's not go into the spotting-it-at-a-yard-line arguement here), it's better to go out to the 45 for the clip than try and squeeze it in at the 40.

[Theisey]

As you have been told: at the back edge of the line furthest from the line to gain.
All the time every time. It's SOP at all levels of the game if you can be sure your chain crew does it as you have instructed them too. Remind them a couple times to be sure.

[Sonofanump]

...and start all new series on a yard line. No sense starting at the 39 1/2. Put it on the 39 or 40.