The economical approach would be to test reception at various locations and elevations... before drilling any holes in your building. A 4' to 6' ladder can be weighted near the base and then used as a temporary tripod that's still fairly easy to move about.
If your TV lacks a signal quality/strength meter, consider using a SiliconDust HDHR type tuner. Until you step up in price significantly, I don't think you'll find a better signal hunting tool. It also makes a great base for a PVR/DVR.
http://forum.tvfool.com/showthread.php?t=820