These general rules of thumb will help you get the best out of your cables and home theater interconnects:

Avoid long cable runs and use the shortest possible runs:
The shorter the home theater cable or AV interconnect, the better. In this respect, keep in mind that a single cable of proper length connected directly to the equipment is the optimum configuration.

Make sure your cables are long enough:
Unnecessary cable length should be avoided, yet keep in mind that in case of shelved system components, if the rear panels are not easily accessible, you should allow enough cable slack to let you pull the component forward and reach the rear panel.

Use DVI/HDMI cable connection when the two connecting devices have them for the best picture quality.

Purchase DVI and HDMI cables that have been tested at the maximum bit rate supported by the HDMI standard over the specified length of the cable.

If multiple sources are connected to a single display use a quality switch that is HDCP compliant. All active components in the HDMI loop should be HDCP compliant.

Purchase only quality cables and switches and only from a source that allow you enough time to try them in your application. This also means that you have to test the cables with the sources and display prior to installing them behind a wall or in conduit. And remember... always handle the cables properly during installation.

Keep power cords away from signal cables:
Power cords can introduce a significant level of interference into signal interconnects.

This being especially true with low power line home theater cables. Therefore, try to minimize as much as possible contact between the two - ideally keep power cables away from signal once.

Ensure correct hook up of cables:
If a home theater interconnect has arrows printed on its jacket, hook it up so that the arrow is pointing away from the signal source and toward the destination. In other words, the direction of the arrow should follow the signal flow from source to load.

Avoid kinking or bending a home theater cable:
Don't try to pull a short cable to make it reach. This is especially important with optical interconnects. This can put stress on the cable connectors as well as potentially cause damage to your cable or system gear. If necessary, buy a longer cable.

Don't keep excess cable lying in loops:
Preferably, arrange any excess cable in an "S" shape or a figure-eight instead; this can help minimize electromagnetic interference.