The complimentary colors (directly opposite the base color on the color wheel) for blue are orange and yellow, remember though the exact hue will depend on the base color. As bright as the Electric Blue is the orange/yellow are gonna be screamin'. Contrasting colors (at right/left angles to your base color on the color wheel) would be green and red. Most of the really eye-catching flames seem to use either strictly complimentary colors or monochrome (varying hues of the same base color) fading to complimentary. The PT in the upper picture uses a purple hue from it's monochrome group (blue) then fades out to complimentary yellow and orange. The lower image shows the use of strictly monochrome hues all within the base color group (blue).
I'm being fairly broad as the HUGE amount of hues/tints and add-ins (flake, leaf, etc.) will provide you with more choice than you could ever ask for. If you've already got a layout in your head I'd take an afternoon to go into the shop and take a look at their books to see what colors/finishes are available.
My only advice regarding color is to pick colors as lively as the base. Dim, soft colors aren't gonna look right on such a bright base. Excluding black or if you're looking at "ghost" flames of course.
