Aside from normal chain responsibilities, I think the single-most important thing you can do is help them understand how they are part of the officiating crew. I have the privilege of working in a position where I attend NFL down judge discussions with their respective chain crews and they meet/greet every single member of the crew with a handshake, eye contact and do a fine job of building a rapport with each chain-crew member. I have never witnessed even a single instance where they have come remotely close to talking down to any of the members. But I understand this is a different level of football and you are often dealing with volunteers who may have a son/daughter playing and want to tell you what you "miss." Remind them pre-game they are assistant officials. The last think you want is to have an argument with them about calls made in the game.
Make sure there's a long, new piece of tape at the exact mid-point of the chain (and don't forget to get your clip back). Ask the box operator to please make sure s/he doesn't move or change the down until you signal. That's huge. When I have worked the position I always make sure I say "if I ask you to move and there's a flag on the ground it's possible I didn't see it so PLEASE DO NOT listen to me." I tell them to point out there's a flag on the ground. Lastly, make sure you take your time in changing ends of the field and never rush and be absolutely sure where you are picking up your clip. I saw a high school crew with an official who was retired from working major college football who placed the chains at the 11 instead of the 16 when changing quarters. It happens!
Good luck.
To pile on to this: When changing quarters, I find guys most often get into trouble when you have an unusual down/distance (specifically, greater than 10 to go, or what is often called "two sticks").
Lets say we are 3rd and 17 at the A-17. LTG is the A-34. The back stake would be at the A-24, and my clip would be on the A-25 (closest 5-yrd line to back stake).
The trick that helped me (maybe it works for you, maybe it doesnt) was that I would wait for the last play of the qtr to be fully finished and any penalties administered, then my process is as follows:
-- I would go to my box man first and talk to him individually. "You are going to the other 17 yrd line. Go ahead and move" (now you only have to deal with the two chain guys)
-- Next, I go to my front/back stake guys. I tell front stake guy, to stay until we pass him. I tell back stake guy to go in front of front stake guy.
-- I grab the clip and verify the marker shows 25, and say out loud, "I am going to the 25. Line to gain is the 34"
-- Once at the new 25, i hold the clip on back side of the 25, and tell back stake guy to stretch and place his stake.
-- Finally I tell front stake guy to stretch, and verify his stake is at the correct LTG, and then setup on my box man at the 17 and start my pre-snap routine for the next play.
I feel like having a routine makes the process more muscle memory than anything. All of that takes less than 60 secs and you should be in place before the R is calling teams out of their huddles.
