There are many many many articles (both from judges about judging, and from non-magic contexts) on both management and leadership. I'm linking to some below. But for me the most important thing to remember is that as the HJ, I should know as much as possible and do as little as possible.
Of course that doesn't mean you should sit at your HJ desk all day and do literally nothing, but exhaust your delegation options before doing stuff yourself. Your job is to be on top of the flow of the tournament, and if you're off to the side counting decklists, unaware that the last result of the round is coming in, you're going to be startled by your own tournament. So let your floor judges do the legwork so you can keep tabs on what's going on in the big picture. Your FJs are also a valuable source of input about that big picture, so ask them what's going on with that lengthy call, ask them to find out information you need for you.
And breaks. Make sure EVERYONE gets breaks. It's sometimes easy to forget that that includes you. Give yourself a break. I'm not kidding in stressing this (or maybe I'm just a control freak sometimes). I've messed this up so many times and have had others tell me ‘but hey, did YOU take a break yet?’. Don't be like me ;)
Edit: forgot to actually paste the links
http://blogs.magicjudges.org/articles/2015/03/17/head-judging-a-pptq/http://www.mtgscorekeeper.com/2015/12/2015-mid-atlantic-judge-conference.htmlhttps://www.mindtools.com/pages/article/newTMM_92.htm
Edited Anniek Van der Peijl (Oct. 26, 2016 08:54:33 AM)