A neck scarf is the easiest way to top off an outfit. I'm showing the 4 ways I use my scarf and how simple it is. I picked up this great silk scarf from Nordstrom for like $12! So duh, I had to buy it. I can't find this exact one in stores but I've linked to one similar.
Scarf: Nordstrom (similar)
Bag: Urban Outfitters (psst, it's on sale!)