Get as close of a color match as possible. Paint your touchup area but take the extra on your brush and "dry brush" it in a large area, 8-12 inches, around your touchup so the paint kind of fades out to the dry wall. It'll hide your touchup much better.

If you take in a piece of paint or wall, at least the size of a quarter, they should be able to use their spectrometer to get a match.

Take a switch plate off the wall to see if paint extends to that area. If it does you can cut a piece off the drywall to bring to the paint store for a color. Or, get a paint deck and match it up to the wall. When you’re ready to paint, keep the touch up as small as possible. You’re just filling in enough to not go beyond the existing bare area. If the color isn’t a good match, extending it beyond the original bare area just increases the problem.

Source- I’m an artist and decorative painter for 25+yrs.

No.

Color match, then paint from corner to corner. Prep work is everything.

It will never match.

If you don’t know the color of the paint it will be tough.

You could try to get a sample off the wall (maybe behind a picture or somewhere inconspicuous) and take it to a paint store or Big Box store and have them match it, but it still probably won’t be perfect. If you do this, pay attention to the sheen. If the wall is glossy and your touch up is flat, it will stand out.

If you can’t get a sample you might be able to match it by eye if you get a “fan-dex” from a paint store—the thing with all the paint colors from a certain brand in it. There are some tricks to matching by eye, but you can do it with practice.

If you can touch up a larger portion that goes all the way to the edge of a wall it will be much less obvious.

It all depends on color matching and then what level of sheen you need. And if actual paint chipped off then the paint isn’t going to just fill that spot and make it look normal. You’d have to build up the missing paint area with spackle or something and match texture and then paint

Feathering. https://youtu.be/KcMR3lnTJOc

Get a bunch of similar paint chips from a paint store. Tape them to the wall with a space between each. Look for the chip that seems to vanish. Then look at the sheen. Eggshell is slightly glossy, flat has no gloss, and gloss reflects a lot of light. Most interior walls are done with eggshell. Then get a sample size of your chosen color. All told you can go this for around $10.

Make sure you get the right sheen also. Flat, Eggshell,Satin or S/G. Take a sample of the color about the size of a quarter and have it matched at the paint store or Lowes. Best bet to paint the wall from corner to corner. If not. Take some out of the can and thin it with a little water. Most times you see the touch up because the touch up is a thicker coat then the older sounding area. Also if the surrounding area was rolled and not brushed use a mini roller, you will get a similar finish.