When designing signs, advertisements or logos, contrast is extremely important. One of the best ways to test the contrast of a design is to convert your colored design to a gray-scale design.  There are many ways to do this, but one of my favorites is to select your design go to Effects > Adjust > Hue/Saturation/Lightness, then pull your Saturation slider down to -100.  If you aren't happy with the contrast of your design, you can manually change your colors or you could go to Effects > Adjust > Brightness/Contrast/Intensity and adjust the settings there.

Tip provided by Joe Diaz, CorelDRAW Master, Graphic Designer and Sign Artist