Stairs, pictures and mirrors oh my!

What's a girl to do with a massive wall in which to decorate?  That's the question, to decorate or not to decorate, and if so how?  People seem to fall into one of two camps, no decoration just wall and of course decorate it.  I don't know where this aversion to hanging things came from but I am petrified to hang something in the wrong place, it seems to blessed permanent!  I want it to be aesthetically pleasing also, but like art, design and decor are a matter of taste and preference, there is no right or wrong answer but people will judge it nonetheless.  As this is my entrance into my domicile it behooves me to use it to set the tone for the rest of my home, but HOW?!  I was thinking a large wall decal on the left of leaves as if they were blowing up the stairs and perhaps the same on the right, or pictures of carying frames and themes.  I am at a total loss as to what to put where on all my walls, now that I have SO many and they are so high!  Hanging these items is all I have left to do to feel really settled in, I just wish I had more input when actually hanging them.  HELP