Milkshakes...

All you have to do is ask people to critique? Magical. :o

I think you should have made the arms bent a bit if he wasn't sticking out his arms spilling the milkshake! Haha. For the legs, I see you probably were trying to make him "lean" on the bent one, but in this case both of the legs should have been straightened.
>> He is also tilting so you should have made the legs wider to balance out that body, or changed the lower half to meet the upper half or vice versa.
For the tail, you shouldn't make it look like he's turned around. The lines that make the body should be closed, showing that the tail is behind him, not sewed at his side.
For shading, yes, you may know where the shading goes but you can't carelessly shade everywhere (coughsaysthehypocritecough). That being said, there's "sharp" shading (I think it's called) and there's what you used here. It looks kind of "artificial."
Maybe next time make the lines you have for the sun the same color you made the sun?
As for backgrounds, I agree that maybe a milkshake stand or something along those lines would be good for the view to know what he was drinking if they didn't know it was a milkshake or you didn't title it "Milkshakes..." Overall it's neat, so keep practicing!

Lol so many big comments XD
I tried to make the legs right though

His arms should be longer. Unless they're straight out, then the perspective is wrong. It looks weird.

Maybe more to the background? I shouldn't really say much about the backgrounds because I'm bad with them. But this is good. Great job.

It's alright I didn't really know what to add for backgrounds though XD I really need to work on arms though XD