In that case, the character is definitely too big for the tiles. Thanks for your input!
I wouldn't say so, although 24x24 tiles wouldn't hurt.
She can stand on a 16x16 box, so the standing position is fine.
She'll likely use up to 32px base when walking/running (The reference here is the collision box, not the art), that's 2 tiles, and that's ok. (yeah, "larger" should have been read as "wider", not "taller" in my former post).
She's a bit high, but that make her look more adult. That's likely not to be a problem, imho. You may have to adjust her attack pattern or the level design to benefit for this additional "exposure" of the head. A quick "duck" frame that make her only 2 tiles high and the option to only shoot at the head's height, for instance, can make it interesting. She's not the kind of sprite that will easily crawl in a 1-tile-high tunnel, obviously (or slide ā la Megaman, morph ā la Sonic/metroid, transform ā la shantae ... name your poison.). I let you judge whether that's a problem for your envisioned gameplay.
I'm debating getting rid of the skirt altogether...
It doesn't read well, true. It will be interesting to animate, btw. She can puff the dust out of it when idle, it will flap when she'll fall down. Design-wise, keep the skirt. Pick a colour that doesn't blend too much into the other things (hint, her eyes&hair colour ?) and make sure that colour doesn't happen to be present a lot in the tileset (errm. It looks like gimp auto-converted the sprite into the tileset's palette ... nevermind
).
The concept art shows a side-tied skirt. That's definitely not what you rendered... and that's much more feminine, imho.
