Going out dresses used to mean one thing: tight, short, and uncomfortable from the minute you left the house. That has genuinely shifted. There is so much more choice now in how much skin you show and how much you move in the thing, and I think it is better for it, because a good night out dress should let you dance, sit down, and get in a taxi without doing the tug on the hem every two minutes.
If you are starting from nothing, go for a midi in a slightly heavier jersey or a satin with some weight to it, in a colour that is not black. Black is easy but it photographs flat and it blends into every other dress in the room. A slip style or a simple wrap cut will see you through more occasions than something with a lot going on, because it does not date as fast and it sits well on most shapes without alterations. Before you buy anything, check the lining, a lot of satin dresses are see through on their own and need a slip underneath that nobody tells you about until you are stood under shop lighting. Check where the zip sits and whether it has a decent amount of give at the hip, because that is where cheaper dresses pull first, and check the armholes if it is sleeveless, since that is where gaping happens when you reach up or lean forward. A dress that looks fitted on the hanger can gape right across the chest the second you move your arms, so if you can, actually raise your arms in the changing room before you decide.
For everyday wear outside of the one night, this kind of dress pairs well with a denim jacket or a blazer you already own, and flat boots in the colder months so it does not read as too dressed up on the way there. I have worn the same going out dress with trainers for travelling and heels once I arrived, which saves your feet and does not show under a midi length.
As for how it wears over time, satin and silky fabrics crease if you ball them up in a bag, so you want to fold them flat or hang them, and a cool hand wash or a gentle cycle will keep the finish from going dull. Jersey dresses are more forgiving and bounce back after a wash, but check the label before you put anything with embellishment anywhere near a machine. Looked after properly, a decent one will see you through several years, not several wears.
If I was choosing a colour to start with, I would go for a deep green or a berry red over black every time.