I was on the receiving end of a prick with an air rifle who fancied himself as a bit of a sniper a long time ago. He took a potshot and stepped back from his window, thinking I wouldn't be able to see him, so I caught a brief glimpse of him standing there.
Unfortunately for him not only was I was extremely pissed off about it, it happened to be the day that the PM was visiting my town.
The police, who arrived within about 25 seconds of my calling to report it (see above) were very nice but weren't entirely convinced by my description of where it had come from until they made him stand in front of his window for me to look up from where I'd been shot at - until I said 'he's brushed the hair gel out and made his hair wet to make it look curly now instead of spiky and changed his jumper as he was wearing a short red Fruit of the Loom sweatshirt that didn't quite meet his wrists instead of a dark blue one in about a size 42 chest. I couldn't quite see his jeans properly, I think they were bog standard mid blue 501s, but he definitely wasn't wearing tracksuit bottoms as he had a belt on with a gold buckle'. (yes, it did all come out in a rush of words - I'd been shot at, I wasn't happy).
'Oh, his girlfriend's in there, too. She's wearing a sweatshirt exactly like that - and he said he'd just got out of the shower, but there's a pair of 501s with a gold buckled belt in the washbasket'.
Didn't even need to go to court, my statement was enough for him to plead guilty, I got several months of very handy payments once he was convicted and the Police didn't have to deal with any more reports of a mystery air rifle twat on that street.
I'm actually better at colours/makeup/hair/clothes and posture than actual features, though - I'll be able to describe somebody really well by their skin tone and undertone, hairstyle, whether they've got permanent or semi colours, the cut, their makeup and brow shape and how they walk/whether they overpronate or tilt their shoulder but not their face - or I'll recognise their accent/voice.
But I've been hypervigilant since a kid for reasons and whenever something has happened, I've been the person who acts, not one who freezes or panics.