I have a HD TV with no cable service and the regular channel that I get they come in clear but as your watching a show the channel skips or it will black out and a massage will come up on the screen that says weak or no signal, what can I do to rectify that.

These are standard error messages that are basically telling you that something has affected the open air transmission of your signal.

A good UHF/VHF Antenna, Height(very important),
If going to 1 TV or Receiver, Twin lead with stand offs is more effective than coax. If going to multiple locations, Use Coax, a Preamp at Antenna. Then a splitter from out on preamp power supply, If going to many TV's, add a distributation amp. Any nearby FM stations may need to be trapped if interference occurs.