Green trousers sat on the "no" side of my brain for years, filed somewhere between novelty socks and anything with a slogan on it. What changed was trying on a pair in a khaki so deep it read almost as brown under shop lighting, and realising it did exactly what navy does, just with more personality.
The easiest shades to wear are the muted, pulled back ones: olive, khaki, a dark bottle green that could pass for black from across a room. Those work with the sort of tops you already own, the greys and creams and stripes, without you having to think about it. Brighter greens, the grassy or acid ones, are lovely but they ask more of you. They want a plain top and a bit of nerve, and they show up in photos in a way that the quieter shades don't, so they're not the ones to reach for on a day you want to disappear a bit. Matte cotton and twill hold their colour better over time than anything with a sheen, which tends to go patchy at the knees first.
Where green trousers are the wrong choice is anywhere you want to blend in completely, work events with a strict dress code, or if you're someone who hates being asked about an item of clothing more than once in a day, because you will be asked. They also show the limits of a cheap dye job fast. A couple of washes in and a lot of the budget pairs go slightly grey at the seams, the colour lifting unevenly, which ages them faster than the fabric itself wears out. If you're buying for the long haul, cold washes and turning them inside out matters more with green than with black or navy, where you'd never notice the fade starting.
Fit is where most green trousers go wrong before colour even comes into it. Because they're often bought as the "fun" pair rather than the sensible one, people size by eye rather than by what they'd normally buy, and end up either too big through the waist or clinging in a way that reads as trying hard. Go by your usual trouser size and check the rise sits where you like it, since a slightly high waist in a bold colour draws the eye exactly where you don't want it if it's gaping. Watch the hem length too, these get cropped and ankle length more than most trousers, and an inch wrong at the bottom either stops them looking deliberate or makes a tall person look like they've borrowed someone else's pair. Worth trying a size either side if you can, because the drape changes how confident the colour looks far more than the shade itself does.
A good pair, in the right green, in a fabric that survives actual washing, is one of those things that quietly changes how often you reach past the black trousers in the morning.