After looking through your gallery, you have some serious potential, so I'll give you a few tips to help you along the way.

1. Don't put your characters in the centre, remember the rule of thirds. Have them slightly to the left or right, and you'll find it looks far better.
2. Decrease either contrast or saturation in pics like this. I get that you're going for a colorful goofy look, but the colors are overwhelming to the eye.
3. When drawing outlines, use that as a guide for your coloring, then in the end, use something like GIMP or Photoshop to add outlines post-color.

I hope these help you out, and I hope to see your art in the future.