I usually go for lighting from above (for exteriors) just because that tends to look natural even at sunset/sunrise since there's always the sky reflecting light from above. I like to add extra visual interest through additional fixed light sources (torches, etc). Scenes tend to look repetitive and boring after a while when they're made up of entirely all-purpose tiles anyway, adding custom sections like that helps a lot. Such light sources also help distract from the unchanging light direction on the other parts of the scene.

If the day/night cycle is fixed rather than dynamic (e.g. it changes during map transitions rather than while the player is just waiting on the same map), then I'd make different versions of the different tiles for different times of day.

Another, more difficult, possibility is to do truly dynamic lighting via normal maps (created with something like SpriteLamp).

Oh, so you did! I guess that's why I only thought of it now and not before - the walls already looked great :'D

I was going to make an edit, but your work isn't posted at 1x, making editing a hassle.

I see the hair now. I think it could read well if it were thicker, and perhaps not outlined (skipping outlines allows more space for the hair to read like a flat lock rather than a tube).

The skirt could read better if you shaded it according to the form it covers rather than pillow-shading around the edges.

For the cape, perhaps try making it cover more of the shoulders, so there's enough of it visible that it doesn't get lost in the details? I think that's the recurring problem with the cape and the hair, they're both so thin in places that they read like outlines or parts of gradients rather than as separate objects. The head-band looks good being a pixel thick because it contrasts well with the hair and no part of it blends in with anything, but objects of lower contrast need to be larger to read well.

Edit: Here's a quick edit with some suggestions for the cape, hair, skirt, and de-pillowing on the legs:

I also merged some of your redundant colours and got rid of a few highlights on the hair that I found distracting.

Moss tends to grow in thick clumps, so I think if you avoid dithering between wood and moss and instead keep the moss in all-green chunks with smoother/undithered edges, it'll look less like spew.

The drop shadow looks nice

I'd really prefer you made your own base tiles instead of using my own, so that you can apply what you like about mine in your own work and make sure you understand it. Plus, mine are a bit noisy since they were intended as just a proof of concept.

I like the new tiles you made, although there's one issue I see - you're using some vertical rock shapes, which makes the floor look like we're seeing it from directly above, rather than somewhat from the side. Keeping all the shapes horizontal helps create the illusion of perspective.

For making new tiles, consider making your rocks have sharper corners instead of having them round like mine, so that they look more like the tops of the rocks in the walls.