Although the triangle pose belong to beginners' yoga poses, its benefits are so great that even advanced practitioners do it from time to time. The pose is not only stretches your whole body but also increases your balance and legs' strength.
Open your chest; correct the spine, making it as straight as possible. Remember the most stretched areas are your shoulders, lower back region and your leg muscles. Of course, it doesn't mean all these areas get stretched in your case; it all depends on your particular condition. For those with low-level of flexibility all these muscle groups will get some load, and if you are generally in a good shape then, probably, only those muscles you haven't worked properly on, will get involved.
Stay in the asana for 30-60 seconds, breathing normally, and then return to the first pose. Now repeat the asana changing the direction - now you need to bend to the left side, doing everything in the same order.
It is important to keep your leg you are bending to fully straight. But if you cannot do it yes, then you can bend you knee slightly, and once you reach the last step in the pose, try to straighten your leg.
There is an alternative to the regular triangle pose when the bending that comes with a spinal twisting. Actually it is not that difficult as it may sound; in fact it is even easier in terms of stretching. The technique is similar to normal triangle pose, but when you start bending to the right side, instead of right palm, you place your left palm next to your right foot, while twisting your spine.
The most difficult in this asana is to keep the balance. In the beginning you can try doing it near a wall to prevent falling on the floor.
Remember that you need to follow your breathing; when bending, exhale, inhale when returning to the first pose, and breathe normally while in the asana.
You can practice the pose daily without any harm to your body. In fact, it is able to not only stretch your whole body, but improve digestion and increase energy by stimulating the spine. As an added benefit of the regular practice of triangle pose, your waistline fat may get seriously reduced.