How is it unfinished? Are you trying to hit a target word count? Because the general rule is “write something as long as it needs to be.” So, if you’re done, then you’re done. But, if you feel like there’s something missing, then you should do these things in this order:
Step away for a while (like weeks or even months) and stew on it to see if you can determine what’s missing. If that doesn’t work—Read it a bunch more times and stew on it to see if you can determine what’s missing. If that doesn’t work—Give it to some trusted friends to see what they say might be missing. If that doesn’t work—Let strangers read it to see if they can determine what’s missing.
Other than that, I hate to admit it (because I hate doing it), but outlining your piece might help you find the holes.
Oh, and if it is that you’re trying to hit a target word count, just add the word “very” a bunch of times before an adjective. It’s very, very, very, very, very, very, very, very helpful.
And as for the CTFD Method, it started as a post here, then went: Crazy. Bananas. Wackadoo. Loco. Insane.