Add a photo filter adjustment layer by clicking on the little camera icon in the adjustments tab. Then, using the drop-down menu in the properties dialogue box, you can choose your filter and make adjustments. I often use a cooling filter to tone down the warm yellows and red tones in my photos.
Simply desaturate your photo by adding a Hue/Saturation adjustment layer to your photo and moving the sliders until you get a look you like. This is a good choice when your colors coordinate, but are just a bit too bright for the collection you are using.
Use any one of the many styles or actions available in the SG Store. These can be found by clicking on the PS & PSE Tools in the menu bar, and choosing from the drop-down menu.