If you decide to use some for your next project, look for color variations to add some pizzazz. Keep your eye out for wood that you can repurpose while visiting local garage sales, flea markets, and estate sales, and scan your local newspapers or Craigslist for notices. Often, people will give old wood away just to get it off their hands.
Be choosy. Look for character in reclaimed wood—knots and weathered wood are ideal for adding a unique look and feel to your project. Grooves in the planks, flecks of remaining finishes, and even gouged or damaged wood will give a finished product an authentic look.
Now, it's time to get building.
Source : http://www.popularmechanics.com/home/interior-projects/how-to/g1479/8-clever-ways-to-build-with-reclaimed-wood/