One of my favorite changes in our living room was the addition of more trim.  I think moulding adds so much character into a space & can be a relatively easy & cost effective way to really change a space.  Using stock moulding profiles from Home Depot, I was able to add a few custom touches that required just a little creativity & vision.
Our gridded wall is a great example of these…
We already had the Picture Moulding detail on this wall (basically just a large rectangle of trim on the wall).  But I wanted to beef it up a little bit…. So I added a second piece of trim to the inside of the existing rectangle.
I installed them flush with each other & once they were caulked & painted, they really do read as one larger piece of moulding.  This is a great way to achieve a specific look or size you are looking for, if you just can’t find the stock piece you need.  This trick also allowed me to have a flat surface that was deep enough to allow the flat gridded boards to sit flush against the new interior of the Picture Moulding.
I also decided I wanted to bulk up our skimpy existing baseboards.  At only around 4″ tall, they almost disappeared into the space.  I used a similar trick for this as well…
I added a 3/4″ piece of moulding about an 1 1/2″ above the existing moulding.  This was attached directly to the wall.  Again, after it was all caulked & painted out (including the 1 1/2″ void in between) it appears to be one solid baseboard that has much more presence in the space.
Here are a few other tricks on installing Moulding in your own home.