Tremulant, lovely pixels, the topmost image looks like a leprachaun from hell *shivers* Also your edits show good improvement. Seems your catching onto the Helm's highlight advice;, adds a nice touch to any image. You might consider highlighting the cane and belt (more or less adding a shine or glare to it, being that everything else has highlights anyways).
As for your other images:
The mushroom head dude rocks, its hilarious to look at. Nice smooth cartoon details. He should probably eat less soap though, tis bad for his health it is!

The Cedric is well made, quite realistic, but I believe there is room for some optimization and lighting corrections:
-dark tones too close together in color (contrasted them)
-a few lighter skin tones were also very close so I contrasted them
-many of your hues didn't follow a good saturation flow (as colors get lighter or darker their saturation shifts slightly aka goes up or down, but they all must go up or down; there are rare exceptions when dealing with unusual lighting however)
-some shadows weren't dark enough so I darkened them
*ex:under the neck for example
-added hair detail near the face itself
-added minor AA to the shirt and necklace
-made his necklace shinier (I think thats gold on the end?)
After editing I still don't like my neck edit alot, somethings just off I suppose. Anyways hope you find this useful.