To improve your skiing technique cross country skiing might help you brush up on the fundamentals.
To master your skiing technique country skiing may be a good place to start.
Even if you're an experienced cross country skier, it can be easy to get anxious if you're in new territory or faced with a particularly grueling trek. Try to relax as you get through difficult areas or when learning something new. Get in the proper cross country skiing position, with your knees slightly bent. Keep your body slightly crouched and fluid as you move.
To make sure that you're gliding properly, make sure that the center of the bottom of your cross country ski is coming into contact with the snow; otherwise you're not using your body as effectively as you can and you'll be wasting energy. When you kick and shift your body weight, stride with the leg opposite the one kicking for the most movement.
Make sure you slide after each glide and don't try to go into your next glide too soon. This will allow your body to use as much of your momentum as possible before working again. If you find that you need a little more momentum than your typical glide can offer, try the herringbone stride. To do the herringbone stride, position your skis in a V shape and put pressure on the inside edges of both skis. Kick off from one leg and begin to glide. The pole opposite the moving leg should be used to help propel you. Continue this movement, alternating legs, to get you through any difficult terrain.
Most cross country skiers use cross country ski poles to get through rough patches and help with stability. If you are using cross country ski poles, keep the poles near you. Don't push them out too far in front of you. Also try to ski without your poles from time to time. You don't have to leave the ski poles at home, just try to ski without using your poles.
If your legs are feeling particularly tired, you can use a technique called double pole. This means that you're using your arms and poles to pull you more than you're using your legs to push. To double pole, plant your ski poles next to your body. Pull, then push with your arms, using your core to move you forward. You will find that you bend over as you do the double pole; this means you're doing it right.
Once you've learned how to wax cross country skis, you'll be able to keep your skis in optimal shape for a longer period of time.