I ran across Bounce Rate articles on the web recently and see that many people are wasting their time with this metric. A high bounce rate can be because:

A high bounce rate in these cases is not something to worry about.

Bounce rate is almost meaningless unless you drill down

Avinash has put forward good ideas but in most cases we need to go further. Drill down to the:

Map this to previous years to eliminate seasonal influences. Then map changes in bounce rate to changes made on the page, traffic source and keyword changes. This will provide further insights. You may find a change you made to a web page that you forgot to track that either caused much damage or increased success rate dramatically

Tracking bounce rate over time can reveal website changes that were overlooked and cause damage. Track by page and by segment for best results.

After your analysis you will find website pages and/or traffic sources to optimize. Don’t forget to track the improvements you made to make sure your changes bring the desired results.