One site that can be used for needle decompression of the chest, or NDC, is the 2nd intercostal space at the midclavicular line (or MCL). You should evaluate the clavicle and draw an imaginary line at the center of the clavicle. 

NEVER attempt an NDC medial to the midclavicular line or medial to the nipple. You increase the chances of hitting vascular structures in the mediastinum by doing this. 

You should also never point the needle towards the heart; insert it perpendicularly to the chest wall. Additionally, you should always avoid insertion directly under a rib. The neurovascular bundle runs along the bottom of the ribs, so the optimal site is just over the top of the 3rd rib.

Another site is the 5th intercostal space at the anterior axillary line (AAL).  The 5th intercostal space is located at the level of the nipple in young, fit males. The nipple level is variable in females – but you can lift the breast and use the level of the infra-mammary fold. The AAL is located at approximately the lateral aspect of the pectoralis major muscle, also more easily located in males.

Either site can be used for NDC. There is no evidence that shows one site is better than the other.