A balanced ski is essential to ripping turns on both sides of the course. It's no use to have a ski that turns great on one side and like a transport truck on the other, so here are a few questions you can ask yourself to help you balance your ski and start carving fluid turns in both directions.
What's the factory setting?
All skis have different bevels, rocker patterns, thickness, width, materials and flex. Once a ski company signs off on a shape, they find the fin setting and binding placement that best complement all the attributes they have built into the new ski. This is called the factory setup. Trust the company you are buying from to find where the ski is most balanced with itself and all its design attributes.
What's your skiing level?
The next setup component is your skiing level. I always try to set up skis so they work best at your hardest pass. As the rope gets shorter you will need to run less fin length, so shallow up a little and move the fin back. This works in reverse too. If the rope is longer, add some length and depth and move the fin forward a little.
How do you ski?
This is where the tweaking comes in. After a few sets on the ski, figure out the side on which you naturally turn better, and detune the ski slightly to help the side that needs love. For example, if you have a strong good-side turn but rotate your shoulder on the offside and the tip rises or the tail turns, run a little more tip in the ski so you feel the ski pulling back in harder. This will help you trust the ski to come back through without having to rotate and push on it. The little that this takes away from the good side will be easy to adapt to after a few turns.