Gallery walls are tough for even the Above Average Joe.  And when the DIY efforts don't look IG-worthy, the whole process is deflating. We know. We've come to the rescue many times while promoting our view that gallery walls are a DDIY (Don't DIY) project. But let's take this one step further and address the STAIRCASE GALLERY WALL. It’s a lil bit daunting. But here’s what you need to know, how to estimate costs, and what you should outsource (and to whom)…