I have an adorable pug, but I can't give much of an advice when it comes to breeders or the dog's look.
I can tell you some things, though.
We got the dog from a pet shop. We told them we wanted one, and they got in touch with breeders, and sent us some pictures of the puppies.
I guess common sense applies here: don't get puppies from a breeder that doesn't inspire confidence.
Pugs are well known for having breathing difficulties, so you might want to ask for references about if the puppies' parents have troubles breathing or not. Mind you, all pugs snore and breathe loudly, but you'll want to avoid serious issues.
I heard it's also good if they have a continuous wrinkle above their mouth. I mean, not various wrinkles, but just one big one. I don't really know why, but I'd guess this is related to breathing and health somehow.
Finally, our puppy was very cross-eyed when we got her, but it got better as time went by, and when she became an adult she wasn't cross-eyed anymore.
A picture from her:
http://instagr.am/p/DBlB4/
Post pictures of your puppy once you get them!
edit: oh, BTW, pugs are SUPER friendly, they'll follow you anywhere you go, and they'll be very happy if you play with them.
They're mostly indoor dogs, because of the breathing issues. Longs walks under hot sun are a no-no.
And though they have short hair, they lose it A LOT.
If I ever had to choose again, I'd get another pug eyes closed. I think it's the best thing my girlfriend and I have done for the last couple of years.