You can use the Crop tool to quickly cut out large chunks of the image that you don’t want to use.

Keep the strength of your finished stencil in mind and create any additional links to maintain its structure when using it.

If you are using newer versions of Photoshop (CS6+), you’ll need to select “Preferences” → “Plug-ins” → “Show All Filter Gallery Groups and Names” before you can see the Artistic filters.