Reach a competent level in your own practice before taking the step to instruct others. As with everything in life, yoga is effective but it will only work if you work at it.
You also want to see the length of each certification program. Yoga sees the mind and the body as inseparable parts of a whole. In this case, you will have to raise the volume of your voice, without over compensating.
And this helps improve the functioning of our organs and our general health. This level of training covers more intensive study of anatomy and physiology, and a deeper look at the different branches of yoga. One of the more important tips for beginners is to let go of your ego.
It would be pointless, if your body were doing the practice while your mind were busy sorting out some other worries. So just sign up.