It's important to note that there's at least one more sprite style in addition to flat (early NES style) and with dark outlines (cartoon style), which's sprites with volume shading. That's my personal favorite style, but it's kinda hard to pull off on the NES due to the low number of colors in sprite palettes. If you're not clever in the way you mix and reuse different hues, or use more than one palette, you can easily end up with sprites that appear to be made out of clay.
That being said, I can't help noticing that your main character is way too dark. There's very little contrast between his clothes and his skin, and considering that the environment where he'll be in is also mostly dark, that could be a problem.
Keep in mind that good use of color in art is not about painting objects with the colors that they actually are (or the ones we *think* they are), but exploring the relative relationship between all the colors in a scene so that everything *appears* to be the color that people expect them to be. Who hasn't seen this image yet
, where squares A and B have the same absolute RGB values (go check in MS Paint if you're in doubt), but due to the context around them, one is perceived as light and the other as dark?
Color is not absolute, it depends on context. This is a video game, where being able to clearly see and identify elements on the screen can be the difference between fun and frustration. It's not because night bars are dark and your character's clothes are black that your only option is to use palette entry $F0 for these things. You can very well calibrate the environment so that dark gray represents the darkest shading in the scene, allowing you to still use black outlines wherever you find necessary to prevent dark things from blurring/blending together. This relativity isn't exclusive to brightness either, the hue is also relative depending on the surroundings, and taking advantage of that on the NES makes a huge difference, since you don't get many hues to work with.