So here's the thing.
Halloween has never been a favorite holiday, just because coming up with a decent costume is something I've never felt particularly skilled at, and doing so stresses me out. The number of costumes I've been happy with over my life has been astonishingly few.
When I was a kid, I dressed up as a vampire a couple of times; my dark hair lends itself well to that, especially if makeup lightens my skin tone. The one I remember fondly, though, is when I wanted to be a mummy. My own mummy (obvious joke) cut an old white bedsheet into strips and wrapped me up from head to toe. It was pretty great!
In fifth grade, my nerdity showed no restraint as I decided to be a computer. I think we put a cardboard box around my middle, decorated up to display a monitor and keyboard. It was probably slightly crap, and I feel like I remember some classmates mocking it, but that sticks out in my head as a time I made a costume of something I loved, just for *me*.
Possibly my most successful costume ever was around 2003, when I came up with the concept of Vampire + Pirate = VamPirate. Not only was it wordplay-based costuming (yay!), but it looked pretty damn great. Sam, Heather, William & I all dressed as VamPirates, with Tish as the VamPirate Slayer.
Most surprisingly effective costume was a couple years ago. My hair had grown out to my shoulders and I had several days' stubble on my face, and Bob pointed out that I could easily cosplay Baltar from BSG. (My doubtful response: "But... isn't that just wearing clothes?") So I put on a suit and printed up a nametag. I was surprised at not only how many people seemed to love the outfit, but also by the couple of people who "got it" even before seeing the name!
Not Halloween related, but one of my favorite costumes ever was during the couple of years when Ryvre & I were doing the Hedwig shadowcasts with Chad & Jenny Byers. I was cast as Stephen Trask's character Skszp, and so got to dress up as a damn rockstar, with leather pants and fishnet top and eye makeup.
And... that's it. Usually I have such a hard time coming up with a concept that I just throw something together, feeling like the result falls somewhere between "eh, it's okay" and "wow, that just looks like a couple pieces dashed together with no thought". One year when I was in a particularly hard place, I decided my concept was "well dressed monkey". Wearing a suit again, but mostly so I could buy and wear a full-head monkey mask. (And thus not worry if my face reflected how I felt.)
Clearly the answer is to embrace what I loved about Halloween as a kid. Take a lesson from that cardboard-box computer, and just do something for me. Not obsess over what anyone else will think, or whether what I've come up with is "good enough".
All told, of course, that's easier said than done...