Arts and crafts are an important part of growing up, and unfortunately for many sissies that period was completely usurped by their male alter egos. Well it's time to get your true ego in on that growth and expression from your youth.
You're going to make a sign to announce that your bedroom is the domain of your sissy side - it is hers. She is the owner. Passers-by will also know that this room belongs to a beautiful sissy. This is the chance for your inner sissy to really express herself for all the world to (potentially) see!
The sign itself can be anything, so long as it conveys that the room belongs to a sissy. It could be something as simple as your name (or "Sissy" followed by your name). It could be something more complex, "Attention: Sissy Inside." Hand-written signs are best, but time-conscious and handwriting-conscious sissies could simply print out a version of the image above and then sign it with their name in marker. Decorate it however you want - hearts, stars, or just your sissy handwriting. So long as the sign is legible and clearly shows that it belongs to you, sissy.
More serious and intrepid sissies might even want to have a permanent sign professionally made to showcase their sissydom (you can always work up to that, sissy).
You're going to post it onto a door into your room. Sissies that live in one room apartments may have to put the sign on their front door. Every time you see it you'll be reminded you're entering an area that should belong to your inner girl. Every time anyone else sees it they'll know that a sissy lives there.
Keep the sign up for at least a 3 days. Don't pull it down on a whim (many sissies become regretful after fapping). Put in some extra work to properly secure it if you can't trust yourself. If you truly respect your inner girl you'll want to keep your sissy's sign up longer (or permanently, replacing it and remaking it whenever it gets tattered).
Without the sign your inner sissy knows where she lives. With the sign everyone else does, too.