For this demonstration, we will be using the following image to make the lady stand out using two methods - color, and focus.
The first step is to duplicate the layer so we have a backup. Then choose the Quick Selection Tool (
). This tool's toolbar will give you the options of changing the brush size. This tool works by sampling the surrounding pixels when you 'paint' using it, and it will make a selectiion of similar pixels. Use this tools to select the lady in our image - either clicking each section, or clicking and dragging around. You may find it easier to zoom in whilst selecting (Ctrl+, and Ctrl- to zoom out). Also, if we make mistakes, we can use the Subtract from selection option on the toolbar at the top (or simply holding Alt and clicking).
Once we are done, we should have something like this:
Now, copy this selection into a new layer and hide it. This will make it much easier for us to re-select just the lady, instead of using the quick selection tool again. When you paste, you should lose the selection, so just Ctrl-click the new layer you pasted into to re-select. Now goto Select > Inverse, and then goto Filter > Blur > Gaussian Blur (on the original layer). You may also try different blurs, to see the effects you can get, but no matter which you choose, only the background should blur, like so:
Instead of blurring (or as well as), with the selection of the background still active, goto Image > Adjustments > Desaturate to get this result:
You may find that the edges are a little too hard, and you get not such a clean look, particularly when using blur. For example, see the top of her head in this example:
We can fix this by Ctrl-clicking the layer of the lady to make the selection again, then goto Select > Modify > Border, choose around 5px. Then goto Filter > Blur > Gaussian Blur, and choose around 2 or 3. This will blur the edges of the lady and we'll have something smoother like this:
Experiment, and see what you can come up with.
More Tutorials: 
