Blue is one of my favorite colors and monochromatic color families to use. Personally, I feel it's the easiest color family to use for any image or season. On the above card, the background stamping is in a lighter shade of blue than the coloring and embellishments. This way it doesn't "wash out" the focal image.
The pink or purple family is the next easiest to use. This time, there is no background stamping, just a strip of a lighter shade of purple to highlight the focal image. The white bow ties in with the polka dots and white frosting on the cake. The yellow brads brings out the flame from the candles.
Depending on the mood I'm in, the card stock and embellishments available, and the images chosen, using the monochromatic technique can bring out the best in all of us; even if we don't feel we've done our best.