Greg responds...

First and foremost, you write. Then write some more. Then do a little writing. Read a lot. Write some more. Read some more. Read a lot. Write a lot. Study story structure. Study great literature. Study myth and legends. Joseph Campbell. Listen to how people talk. How they really talk. Learn your craft. Get a kick-ass education. Write. Read. Write.
Get copies of animation (or other television) scripts. Learn the format.
Write spec scripts for shows that you like. Try to use those specs to get an agent. Then your agent can use those specs to get you work. Write more specs. If you can't get an agent, send the specs to production companies that you admire. Don't send a Batman spec to Warner Bros or a Gargoyles to Disney. Legally, they can't risk reading those. But you can send Batman to Disney and Gargoyles to Warners. (I know it sounds weird. There's a real good reason for this, but it's a whole other question, so for now just trust me.) Actually, you shouldn't be writing a Gargoyles spec at all, since that show isn't producing new episodes now. You don't want your spec to come off as yesterday's news. Keep reading. Keep writing. Try writing a pilot script and a short bible for an original series. Try using those to get an agent or work (any work, you need credits on your resume.) Oh, yeah.
PROOFREAD. PROOFREAD. PROOFREAD. Read your own work aloud, you catch more mistakes that way. Read. Write. Write some more. Get used to a lot of rejection. A LOT OF REJECTION.
That's the best advice I can give you except this: writing for television is an extremely difficult career to break into, let alone succeed at; so if you don't really have a PASSION for it, then do something else. You'll need that passion to see you through a lot of dark times. If you can be happy doing anything else, then do that other thing. Otherwise, good luck.