Step 3: Create a set up
I have great landlords so this wasn't a problem for me, but if your landlords are paranoid or mean, you should avoid putting any decorations on the building itself. Or ask for their permission ahead of time.
Try to leave work a tad bit early if Halloween is on a week day, and put up your decorations using strong tape that won't damage anything so that you're open for business while it's still light out. Make your set up visible to trick-or-treaters who might be looking down your block to see if it's worth walking. But obviously, don't obstruct the sidewalk. People should be able to get through with a stroller, a small child and a dog with no problem.
Ask your neighbors or people passing by for their advice if you're not sure about your artistic direction.