Plays Well With Others...
What kind of food coloring are you using? If you pick up some paste/gel food coloring you can get more intense colors. A little goes a long way, and it stains something awful, but with some toothpicks you can keep it off your fingers. It's what I use when I want REAL color.
I don't think you can buy it at the grocery store, but check the craft store with the cake decorating supplies or go to a bakery specialty store.
I used gel. :( I actually found it at Super Target. It was in little squeeze tubes. I used little tubs of it for the halloween cupcakes. Maybe that's the problem. Maybe the tubs are better.