One great thing I learned from Ian Cross, and it's mentioned also in Sherman Keane's "Practical Techniques for the Recording Engineer," is to never set the singer up facing the booth (or the producer if there is no booth). While it's important for the singer to be able to turn slightly and make eye contact with the control room, they shouldn't be staring right at anyone while trying to perform. Especially since people in the booth tend to talk about other things and space out while the singer is tracking.
I refined this a bit by spending lots of time setting up the vocal station. There should be a place for a drink, a place to put the headphones down, tidy cabling and something pleasant to look at. Somewhere to charge your phone, nothing to squeeze past or trip over, etc. And as few mics as possible - It's popular these days to set up three or four vocal mics for a shootout, and then leave them all set up for tracking, or track to two mics. I think this is a mistake - choose a mic and go with it. I think singers can be intimidated by the sight of several mics, several stands, all the cabling, at the very least it's distracting. There are also some easy ways to avoid using pop screens, by positioning the capsule so it's out of the wind path. Have the singer sing slightly over (or under if it's hanging) the mic - position it so this is in a natural spot for them. Added bonus, you don't have to high-pass as much.
Similarly, use Omni on singers whenever you can get away with it. Giving the singer a bit more freedom of movement can really help the performance. Standing in one spot and eating the mic is only comfortable for long-time stage performers who have tailored their style to it.
