I am interested in finding the best way to have my digital photographs printed. I know there are many ways to have it done, but I want to find a place or site that can print photos suitable for frame and sale. Any advice would be greatly appreciated
I've had the most success with AdoramaPix, for larger prints and fine art applications—I really like their metallic paper.
For small (8x10 and under) I've found Walgreens to be quite good, they are convenient for me, because I can upload my pictures to their site and go pick them up in an hour or so.
Rather than trying to look for issues, try to look for positives.
Then there are only really two points to consider - the first is a big one, copyright, what rights do you grant, does the company who offers the service take? (I.e. do they "take" (request and are granted by you by accepting the terms and conditions) more rights than required to offer the service they do?
Secondly, once you have a service that seems suitable, what do other people think of it? A bit of googling really...
I have printed some images via Artflakes and found the prints perfectly suitable (prints only, no frames etc.). Whitewall is another big name with German roots. 500px is I think Canadian and also well respected - prints are canvas only last time I checked. Flickr teamed up with HP on a service called "Snapfish" if I am not mistaken - no idea about the qaulity. Fotocommunity allows paid members to sell images - at least the German branch, I'm sure the other countries do too, being a photographer-centric community I#m sure the quality is at least acceptable but possibly quite good. Other big names are Photoshelter and Zenfolio.
If you have a website, fotomoto might be an option... And there are always your local print shops as well.
In the end, nothing will allow you to avoid doing some in depth research on the topic to find the service that suits your need best.
I have just thrown in some names to get you started - the list should not be considered complete or absolute, these are just the services I know of, off the top of my head.