Where do you print?
 

So where do you all get your shots printed? Walmart (walgreens... etc)? A local photo printing business? Upload online and get your prints mailed to you? I'm just trying to find out the best way (ie. quality and convenience) to get my prints for my customers.
Also what do I need to know about the specifications of the photo for it to be of the best quality for printing?
Your responses are appreciated! ;)