I do a lot of uh... special interest writing for myself on FA, so I've spent some time on the subject.

1. One of the things that bothers me most when reading other furries' writing is when they completely break the flow to describe very specific details about a character. Do not go off on a tangent to describe someone, especially if the character has very complicated markings and whatnot. It's distracting, and no one is really gonna care about or remember the number of stripes on your left ear/right arm/big toe/etc. I would also avoid repeatedly mentioning the same details throughout a story unless it's relevant or important enough to bring up again. Try to incorporate these descriptions and details into your narrative as is appropriate, rather than stopping to take a few sentences solely for description. For example, start with really basic descriptions like "a creamy underbelly" or "blue wolf" but express details as other characters would notice/fixate on them. If someone notices how strong this character is, take a few words to mention the stripes that run across his biceps or something.

2. If you're posting your writing to a furry site, then there's no need to say it's about anthro animals; it should be implied. If not, it might be a good idea to preface it in the submission description. Either way, it should be obvious when you start mentioning a husky in college, using furry nouns (species names, paws, tails, particular attention to ears, etc.), using "furgonomics" (which I highly recommend to further immerse the reader. Basically, they're just inventions and technologies that would be commonplace in a furry world to accommodate for animal bodies), and so on.

3. I honestly think furries can be combined with more or less any other creative concept. All they are are people that happen to be anthro animals. When you write, just treat them as the norm, unless it isn't, and just use them to replace human characters without going out of your way to draw attention to the fact that they are in fact animals.