Layered Navigation is a straightforward extension, which replaces standard catalog filters immediately after installation. Basically, you can work just from the box.
However, there can be things, that should be tuned-up.
- Layered Navigation should be seamlessly integrated to your theme. Visit General and Highlight section of Configuration, and fit layered navigation to your theme.
Do not forget after each change to clear cache to make changes apply.
- Review your products attributes, and set as Filterable those, that you wish to be added to Layered Navigation.
- Some of attributes can have too much options to select. To optimize your navigation, use Links Limit.
- You may wish to make navigation more attractive by changing selection widgets to images. Use Widget Override feature for that.
- Configure additional filters, such as New Arrivals or On Stock using Additional Filters section of configuration.
- You can also make links in Layered Navigation Widgets more SEO-friendly, which will help web-crawlers index your store more effective.
This should be a good start. Refer to corresponding sections of this manual to know more.