I'm lousy at palettes, too! Although generally I like to do either a bunch of cool colors, with one or two small warm highlights, or the opposite--a bunch of orangey, warm colors with a turquoise highlight.I googled "color palette" and came up with a couple good links:http://www.farfromfearless.com/wp-content/uploads/2006/11/palette_all.jpghttp://jeffmellem.com/wp-content/uploads/2009/07/ColorPalettes.jpghttp://farm3.static.flickr.com/2208/2104315150_2f0a36d17a.jpgColor palette generator:http://www.non-solo-arte.com/color-palette-generator.htmlAlso, I would google something like "on-trend color palettes", so you get the latest colors that are in style for upcoming seasons. That will help your work sell. Hope this helps!
p.s. I LOVE your sketches! They are going to be awesome!!!!!!!!