For feng shui, each home and room is made up of areas, or corners, which focus on certain key traits. The money corner of a home, apartment, or room is the back left corner. That is, when you walk into the home or room, look ahead and to the far left. That is the area you want to focus on for money and wealth.
In this corner, you want to first off have it be organized and clean. This is about your life's prosperity. You want that to be moving forward, in good shape, and healthy. So dust and neaten the area.
Next, look at the items that are in there. Are they things that make you think positive thoughts? Pull out anything that would be dragging you down.
Money related symbolism does well here. Some people like to put coins. Other people think of coins as "spare change for pan-handlers" so for them coins would be negative, not positive. Some people think of gold as wealth. Others think of gold as old-fashioned and have more modern ideas of wealth. Whatever it is that brings to mind wealth for you, this is the place to put those items.
The traditional colors to feature here are green and purple. Green is the color of money in many cultures. Purple is the color of royalty and prosperity. But again, this varies from culture to culture. If in your mind red is a powerful sign of wealth, then go with that. It's important that how you decorate this area resonate with YOU. If, to you, green signifies a granola-crunching poor person who has to scrounge for a cup of coffee, it probably isn't a good match for your needs.
It's good to have metal items in this corner. Avoid having too much water.