Neutral means white, or off-white or greyish depending on the tonality of the piece. Fling on a black metalic frame, and you're home free. Try coloured top mats- suede mattes are particularly rich in colour. I use suede mattes all the time for my personal collection. Try zany frames.
Frames can be multi-coloured, or beautifully textured with leaf carvings, daisy patterns, etc.
Usually a simple shape like a diamond is best. Panelling is another option. The framer cuts a very thin area into the top mat to reveal the colour underneath. Usually in a rectangular pattern. Try a fillet.