The thing nobody mentions about a good jersey skirt is what happens around week three, when it's been through the wash a few times and the fabric relaxes into you rather than the other way round. It stops looking like something you put on and starts looking like something you own. A stiff new one sits slightly away from the body for the first few wears, and then one day it just doesn't.
Mine gets worn with almost anything that isn't trying too hard, which is most of what I actually own. A plain long sleeved top tucked in, a heavier knit left loose over the top, trainers on a normal day and boots when it's cold enough to need tights underneath. It's the kind of thing that doesn't ask the rest of the outfit to coordinate with it, which is more useful than it sounds when you're getting dressed at speed. Before you buy, check the weight of the jersey rather than just the print or the colour, because a thin one will cling in a way that shows every seam of your underwear and a very heavy one can sit stiff at the hip and lose the drape that's the whole point of a jersey skirt in the first place. Check the waistband too, whether it's a proper wide elasticated band or a thin seam that will dig in after a few hours sitting down, and have a look at the length against your actual legs rather than the model's, because jersey has a habit of dropping half an inch within a week of wear.
If you've got none of these, start with a midi in a mid weight jersey, nothing clingy, nothing stiff, something that skims rather than hugs. It's the easiest length to get right and the one that works across the most situations without you having to think about it twice, which matters more than any of us like to admit on a weekday morning.
On colour, I'd always steer towards the ones that don't shout. A proper navy, a soft charcoal, a brown that reads almost like coffee rather than orange, these wear well for years because they don't date and they don't fight with anything else you own. Black is the obvious answer and it's obvious for a reason, but it can look a bit flat and uniform on its own, so I'd rather have one of the quieter colours in heavy rotation and save black for the one that needs to go with absolutely everything.
Tomorrow morning I'd put mine on with a cream jumper and old trainers and not think about it again until I got where I was going, which is honestly the entire point.