1. Most of the new polyester strings are not designed for easy volleying. If you play mostly doubles, with a lot of volleying, perhaps polyester strings are not good for you.
2. Many pro players who play the baseline and net (all-court game) use a "Hybrid" string combination. This means a polyester string for either the main strings or the cross strings, combined with a synthetic nylon or natural gut for the other strings. For instance, Roger Federer uses gut for the main strings, and a polyester string for the cross strings. Several pros use gut for the cross strings and poly for the main strings.
3. Today's racquets are very strong and the head is very strong and stiff. Therefore, the string tension is quite high after the stringing is complete. I recommend that you study the recommended string tension range for your racquet, and try to choose a tension closer to the lowest tension of the range. Sometimes the stringer will automatically string to the tightest tension of the range because customers feel that a looser tension is a poor string job.
4. String tension is a personal thing, but here are some guidelines to consider:
a. Tighter tensions reduce power and depth of shot.
b. Tighter tensions also reduce amount of spin that can be applied to the ball.
c. Tighter tensions increase shock to the player's hand and arm.
d. John McEnroe has used mainly low string tensions throughout his career. John strings his racquets with gut at @ 45 lbs. string tension. This allows the racquet to do more of the creation of power, giving him better volleys and spin on his serves.
e. Pro players who hit much harder than John use string tensions more in the 60 lb. range. This allows a fast loop swing to have a greater depth control.
5. Racquets that are extremely lightweight are not good for most players. The lighter the weight of a racquet, the lower the overall power, especially on short strokes such as volleys and blocked service returns. There should usually be a balance between weight and maneuverability, in order to get the most from your racquet.