Candy is the hardest of any paints to apply properly. Like Matt said, to get the acquired effect you are looking for a base coat is need for candy colors. You can put a white base down which will make the color really bright. If you use a silver or gold base, you will have a metallic look under the color. But in any case, you do need to have a base.
And lastly.....you can't just scuff and paint candy. The metal MUST be smooth as a babys ass. Candy is so transparent that any minor scuff will show thru.
Remember............a paint job is 95% preparation and 5% painting.