Changing Drive Belt

So, I'm going to be changing the serpentine belt on my 2008 V6 Tacoma. This will be the first time I will be doing this on this vehicle. How will I know the belt tensioner is tight enough, or maybe even too tight?

 

It's self adjusting. I did this about 2 years ago and I think I went from the bottom just remove the skid plate for better access. here is a PDF file hope it helps out.

 

I think I went through the bottom because I used a long handle ratchet to release the auto tension pulley and it was easier from that side. Hey if somebody knows how to do it better and faster then more power to them.
good luck folks.......