The first thing I do with a green skirt is hold it against my own skin in daylight, not shop light, because green is the one colour that splits instantly into "yes" and "absolutely not" depending on the yellow or blue running through it. Olive and forest sit close to my colouring, a bright kelly or bottle green does something unflattering to my face that I still can't fully explain. So that's the check. Everything else is secondary.
Once the shade's sorted, a green skirt earns its keep in the bits of the year other colours struggle with. Olive and khaki tones move straight into fine autumn weather, worn with boots and a jumper the colour of builder's tea, and they don't look remotely seasonal come an early spring day either, which is more than you can say for most browns. A deeper bottle green does proper evening duty, the kind of thing that photographs well under low light and reads as deliberate rather than desperate. Where it struggles is high summer, when anything heavier than a cotton or linen weight sits hot and the colour itself starts looking a bit wintery against bare legs, a lesson I learned wearing a thick olive midi to a July barbecue and spending the whole afternoon regretting it.
As for what to keep it away from, mustard and rust are the obvious offenders, both of them pulling warmth out of a green that's trying to stay cool, and the whole thing ends up looking like it was dressed by committee. Khaki green worn with khaki green elsewhere on the body, a jacket say, just flattens the outfit entirely and you end up looking like you're heading somewhere with a clipboard. I also wouldn't put a busy floral top above a patterned green skirt, not because it's a crime exactly, more that your eye doesn't know where to land, and the whole point of a good skirt is giving it somewhere to land.
The honest limit is that green, more than most colours, depends entirely on getting the exact tone right for your own skin, and a skirt that looked gorgeous on a friend can do nothing at all for you. It's also not the colour to reach for if you want something that disappears into an outfit quietly, green always announces itself a little, which is either the whole appeal or the reason to leave it on the rail.
Would I still want this if the lighting in here is flattering me more than it will on a grey Tuesday outside?