Stay away from the trees until you are ready to take on the challenging course. Spend more time riding in open glades and practice your turns and control. Perfecting these two things will come in real handy once you actually move into the trees. Riding at top speed through the speed while depending on nothing but luck can result in nasty consequence. If you are lucky, you will walk away with a broken nose only, but if you are unlucky, you may never walk again. It is good to be safe than sorry and that is exactly why you should remain patient and perfect your riding, control and turns before going for the trees.
Once you believe that you are ready to ride through the trees, look for the slope that is not very steep and ride down it. The relative flatness of the slope will keep you from gaining too much speed as you approach and ride through the trees, thus allowing you to maintain control, stop in time when dodging a tree becomes impossible, or making a carved turn on time.
Remember to keep your eyes ahead instead of looking at your sides. You may down riding through the trees with friends and have a strong temptation to look in their direction to shout something. However, keep in mind that if you become distracted, you will increase your chances of crashing into a tree drastically.
Instead of looking at the tree that you are approaching or passing, look as far ahead as possible. This will allow you to have sufficient time to take evasive action or prepare yourself to turn in an appropriate direction to avoid the trees.
Do not increase your speed too much. Even though going at a fast speed will be thrilling, you should refrain yourself from gaining too much speed because of the risk involved.