Buying or renting good gear is one of the most important factors in ensuring you've done your part to make the experience the best. Since you can't control the snow, that one has to be left up to Mother Nature.
Before running out and buying any old ski equipment or renting things without knowledge, it's important to understand that making sure things fit right can really mean the difference between a good run and a bad one. If the boots are wrong, the skis too long and the poles are ill fit, control will be hampered and this of course can mean unnecessary falls or just a difficult time on the slopes.
The poles themselves are probably the most basic of required ski equipment, but they're very important. Poles enable beginners, intermediate and even advanced skiers to maintain balance and can help a skier avoid falls, or at least recover from them. So, it's plain to see that poles are pretty important pieces of equipment.
Not just any old pole will do. Poles need to be of a proper length for the person using them to be effective. Plus, they absolutely need to be designed for skiing. A stick might work - sort of - but not in the manner a well-designed pole will for helping keep balance and stave off those embarrassing tumbles.
When standing in a basic ski stance, poles placed with the grip in front of the feet should allow the forearm and upper arm to be positioned at a 90-degree angle. When ski poles are too short, they cause improper posturing that can be dangerous on the slopes and effect balance. If they are too long, they effect basic maneuvering as well.
They are a pretty basic piece of ski equipment, but if the poles are wrong, the whole run likely will be too. Make sure the poles you rent or buy are the right size or can be adjusted to become so.