There are improvements that could be made to pretty much every element of this piece, but let's start with the palette. It looks like you're making light green-blues (candle/face) and light purple-blues (hood, leftmost bricks), which will help differentiate different elements of the scene, but in my opinion, they clash. Often with a palette, it can look good if the darker colours move more to the cold parts of the spectrum (blue) and the lighter colours towards the warmer (red/orange).
Most of the image doesn't give any impression of depth, apart from the candle. However, the 3D effect there is a bit confused.
The flame and its surroundings are the darkest part of the candle. Unless this is part of the story somehow it seems the wrong way round.
You're using highly contrasting colours on your tiles to make both the surface detail and the cracks. The shapes you're using to do so are also a bit noisy. This makes them look like deliberate designs on the tiles, and makes the image more confusing to look at.
This is just a palette change, with a subtle hue shift across the blue, and a separate, smaller palette for the desaturated greys (for the alternating tiles)
Using two shades close to each tile's background colour, I've made some smoother surface detail for them. This is mainly by making larger shapes with the lighter shade and then smaller shapes with the darker shade. What makes good shapes? Shapes made by pixels of the same colour next to each other are called "clusters" and there are rules and techniques you can learn to start off making them look good. But a lot of it is practice and trial and error. I'm sure you can find some good tutorials on clusters if you look around. A good starting point might be the pixel art primer on Pixel Joint.
http://pixeljoint.com/forum/forum_posts.asp?TID=11299You may notice that the character is already a little bit easier to see because the background has less contrast. And that's without changing the colours of the main character, or the main colour of the tiles.
Here I added some shadows to corners or edges of some tiles, to make it look like some are higher than others. I also added some cracks. To make the cracks look better, disrupt the edges of the tiles (as if some pieces have cracked off and been lost) where the crack meets the edge. Also, pick one side of the crack and make it lighter than the other. That will make it look like it's catching the light.
These are some alternative shapes you can use to base your candle on. Doing this is quick work with the ellipse tool. The difference is that ellipses give a good impression of something circular seen at an angle, while the candle base you used looks like a rectangle with rounded corners.
I didn't want to spend too much time on this, but here's an idea for a candle. The drip is the same shade as the rest of the wax, I'm just using other shades to define shadow and highlights. Candles can have an internal glow where the flame lights up the inside of the wax. However, the wax in front of the flame looks darker in comparison, as it's silhouetted against the flame. Flames are bright! They are made of concentric shapes starting at the tip of the wick. The part most in shadow will be the lower part of the candle, as it's furthest away from the flame.
If you find any of this helpful, let me know and I'll have a go at the main character. Currently, it has no depth and is completely symmetrical. This makes it look like something constructed rather than something natural, to me at least.
Edit: Silly me, drawing a flame from memory. I forgot the brightest part of the flame is above the wick.