Light is the most important factor. Hot sun will burn the leaves but too little sun will reduce flowering. Dappled light is best. In frosty areas, cymbidiums can be grown indoors, but must be in a well-lit position.
Cymbidium leaves should be a light apple green. Deep green leaves may look lush but are usually an indication that the orchid is in too much shade.
The ideal is to have your orchid in shade for the spring/summer period and move it into a bit more light for late summer and autumn. Keep it out of strong winds or very exposed positions.