Received my first cel today

From what I can see, it's stuck on a blank sheet of paper. Some dealers store cels on thin rice paper, figuring if they get stuck to that, it's no big deal: just dampen the paper and it will come off.

If it's the sketch, then that's different, and you ought to try to get it off without too much damage. An old photo (picture side toward the cel paint) is the best thing I've found to work between the two and gently pry them apart. But check for paint loss. If it starts to come off onto the paper, then stop and leave it where it is.

Most multi-layer cel sets are stuck together. The cel paint sticks to plastic like nothing else made, and so long as the two are stuck in the right place, or at least not too absurdly out of whack, then you should leave them together. You certainly will suffer paint damage if you pull them apart.

If you frame it, be sure to get ultraviolet resistant glass and hang it on a wall away from sunlight or fluorescent lights, or the trace lines will fade quickly and irreparably.

And congratulations! The first one is always a thrill ... as is just about every one you'll get from now on.