Author has written 10 stories for Naruto, World Ends With You, and Fate/stay night.
Forgive my whimsy. I've scarcely finished anything but a few one-shots on this site. Perhaps I'll finish something... someday.
When Leaves Fall - ETA 4 weeks (dunno, finals coming up for me; going to make next chapter extra extra long)
In the Wake of Waves - ETA 2 weeks (above applies)
Icha Icha Tensei - Third Chapter: Sporadic, part of a chapter written.
Everything Else - Dead or Finished.
Here are my personal, basic tips - the key to being able to write well. Well, at least fanfiction (which I guess isn't saying that much). You're welcome to disagree, but this is what works for me, and what I look for in most of the stuff I read.
1. Consistent tense. If you're using past, use past for the whole fuckin' story. I don't want to read "he was doing something" then "he is doing something" in the same paragraph. When you become really good, you can afford to jump all over the place and shift tense, but you need to be good. It's far easier just to stick to one tense, so be aware of what tense you're using.
Also, past is a tense most people feel comfortable using, but I think the present tense is stronger. If you can, try to use that tense instead, as action is conveyed better in it. Also, because if you use past tense... you eventually have to use ridiculous tenses like the "perfect past" (He had had done something; yes two hads, how is that even natural to us English speakers? Gah).
2. Stick with the active voice. This one is tough. I have to deal with it all the time. But basically, reduce the complexity of what you write. "He was fighting Orochimaru." Doesn't tell me anything really, "He kicked Orochimaru in the face." Does. Was is passive, Kick is active. You as a reader can visualize a kick, but was is this vague verb that doesn't really "mean" anything concrete. Active vs passive is a little deeper than show vs tell.
3. Screw grammar! Okay, it's important to be proficient in the basics (your vs you're, it's vs its), but I mean, there's NOTHING wrong in my opinion with disregarding most other conventions. It's perfectly fine to have a complete sentence without a verb, or a subject, or an object. If the sentence has meaning, and it's well-crafted meaning, then it's good. Maybe it sounds odd every once in a while, or breaks up the flow; but that can be good. There are times when you want effects like that, where you befuddle a reader or call attention to a turn-of-phrase. Fiction isn't a term paper, it's prose-y.
4. Description. I guess most people in fanfiction take description for granted, maybe some people don't even like it, but I think you need to ground your reader in the thick of things. This means describe. Spend at least a sentence telling the reader what the protagonist looks like. Keep the reader updated on his physical condition. As well as the looks of the other characters; even if we know everyone has some visualization of them already, nobody is truly static. Extension: Good description is active. It's tempting to say, "She wore a pink dress." Because that's what she's definitely doing, but it's ten thousand times to say, "A pink dress squeezed at her butt and billowed at her breasts." That tells you the person is wearing a pink dress and describes how it fits her body. "Wearing" something is pretty passive and doesn't tell the reader a whole lot.
5. Stay away from some popular fanfiction "traps". You should never use bold/italics/dollar signs/whatever to indicate a flashback is taking place or when some god-like character is shouting at somebody. I hate that. It pulls me right out of the story. You don't need that junk. Use words to describe the sound of a voice. If you need a flashback, create a logical transition for it, not a series of hyphens. I maybe abuse the whole "character hallucinating the past" mechanic too much, but it's effective; if somebody is recalling something, make it dramatic. If they're upset their best friend died, have the best friend show up right next to them, only for them to disappear the moment they blink. That sort of stuff is captivating and draws the reader in.