Here's a good reference pic from artist kiraxlee. The head's a bit too wedge-shaped, but the overall look is good, and I like the vest, tail, and mood of pic.
Another good reference pic, from Coyotepuck: This one's got the best head shape:
Very basic description: A anthro canaan hound/dingo-type dog with a lion's tail. With blue-tinted 19th century glasses, round frames. Here's some good Canaan hound pics:
Fiddling details: Face: Pale muzzle, darker ears, top of head, mantle. I'm not really that concerned there! Red-brown eyes, blue glasses. No "mane" or "headfur."
Clothes: Usually wears an ornate ethnic vest, embroidered, somewhere between gypsy and polka. How much detail is purely up to the artist's patience :) I like the pattern on the second of these vest illustrations, but the cut is from a waiter's uniform.
Beyond that, tends to wear scruffy jeans, tee shirts with a teleportation theme (Nightcrawler's "BAMF" logo, "beam me up", or something). These aren't really important, too much detail makes for busy pictures.
Coat: Back, sides, most of legs are on average a light brown. Belly and throat are labrador-dingo colored creamy gold.
Accessories: The only one that's really important is the blue glasses - round blue-tinted specs with, if it's relevant, straight legs:
Other body notes: Tail is labrador-length, but narrower, with a leonine tuft at the end, dog-flexible but not cat-flexible--the tuft would be halfway down calf on a human body shape).
If naked and this is relevant, groinal parts are canine. May be wearing some leather cords loosely bound around base of tail, because that look amuses me.
General attitude--explorer/traveller, with a generally thoughtful expression but not a lot going on upstairs. "Surfer and backpacker with a second-hand copy of 'Howl' trying to pick someone up by faking a philosophy degree."
Also, his species (again, old school D&D) teleports a lot--one artist shows them teleporting in a flash of light, for what that's worth, which is very little. I don't think it's important, since that's hard to represent graphically, but it's part of the character.