.lovely.layers.

I do a lot of layering in my costuming, and my goal is to do more. In part it's a product of my frugality (read: broke), and in part its a product of my clingyness and indecision. I really like being able to use the same piece for multiple costume combinations. I know a lot fo dancers who don't do this - there's a costume and it's that one costume and the parts for that costume are only for that costume.
Which is great - especially when it comes to packing costumes since everything will live on the same hanger and you can just grab it and go.
But I really like to mess about and play with my parts and pieces and find new ways to combine them.
Take, for example, my blue velvet hip scarf.
It was a gift from a friend and I wear it All the Time.

It's the fabulous-ness of basic color theory. Colors change depending on what you layer over them and put next to them. Lighting has a stark effect as well. 

This hip scarf is so worn out now that I have to put it on with a safety pin - note to those of you with velvet hips scarves, it might seem obvious, but don't put it in the washer no matter how stinky it gets. Hand washing is your friend.
I pick pieces like that up all the time - its sort of how I shop for everything.  Just keep a weather eye open because you never know what you're going to run across.

Of course, all of this layering and all of these separate pieces run a risk - that you're going to forget a part. I nearly almost always do.  I haven't found a good remedy for that yet, aside from not waiting until the last minute to pack.
Good luck.