How to fly your flag at half-Staff:

• Most half staff days suggest that the American flag is at half staff from sunrise until sunset on the days of the order. Memorial day is the exception where the American flag is at half staff from sunrise until noon.
• When raising the American flag to half staff on a vertical pole, always raise it briskly to the top of the flagpole for a moment before lowering it. When taking it down for the night, raise it to the top of the flag pole again & lower it to the bottom.
• With a telescoping pole it is acceptable to put the USA flag on the second set of rings instead of the top set. In this case the top set would be left empty.
• When the United States flag is flown at half-staff, State & other flags should be removed or flown at half-staff too.

If your flag can't fly at Half-Staff:

• For flags that can't be lowered, such as those on many homes, the American Legion says that attaching a black ribbon or streamer to the top of the flag is an acceptable alternative. The ribbon should be the same width as a stripe on the flag and the same length as the flag. Order yours today.
  
• For a wall mounted flag, three black mourning bows should be attached to the top edge of the flag, one at each corner and one in the center.

Courtesy of: Gettysburg Flag.com