Above the roof in such a manner that the roof and house are not impeding and blocking reception in the directions of , North West , West , South West , South , South East , East.
Install a ANT751 or Antenna Craft HBU11 antenna aimed at about 112 degree magnetic compass direction.
Here is how to aim antennas ,
http://www.kyes.com/antenna/pointing/pointing.html.
A antenna system amplifier will most likely not be required.
Here are some places to buy antennas and etc. .
http://www.solidsignal.com.
http://www.amazon.com.
http://www.antennacraft.net.