Avoid using background images (stick to white or transparent)
Use simple fonts (sans serif works best for graphics)
Stick to a color scheme unless necessary (for more complex data)
Space components apart equally
Avoid 3D shapes unless necessary. This is because, done improperly, 3D components can easily skew data and distort perception and interpretation. For example, a 3D bar may be significantly greater in volume than a 2D bar in area.