I mulled it over for a while, and I've managed to come up with twelve great ways to have agents/the public not laugh in your face when you talk about (your) writing. If you disagree with them or want to add one of your own, feel free to leave a comment with such. The tone is pretty tongue-in-cheek, but all of the points are valid enough. Again, feel free to disagree! Never stop thinking.
1. Do not, do not call yourself a writer unless you write frequently and are able to produce examples of past and recent work on demand.
2. Do not call yourself an "aspiring" anything. That's just telling everyone what you wish you were, not what you currently are.
3. Accept criticism, even if it hurts. When you stop improving, you start failing.
4. Do not rage. There will always be someone to dislike your work.
5. There will always be someone better than you. Expect that.
6. Read. You can't write unless you read.
7. Don't worry, your criticism will always piss someone off. It isn't just you.
8. Don't be gentle. Be rough.
9. Don't try to make everyone happy. You won't. You'll never know your complete audience, anyway (unless the only people reading are people you personally know).
10. Remember: writing is a craft before it is an art. You can't create an absolute monstrosity and pass it off as something Picasso-esque. Not unless you're good. Real good.
11. Enthusiasm is great. Bragging is not.
12. There will always be someone who won't take you seriously.
See? I'm starting to take you seriously, already.