Howdy! I was recently asked the procedure I used for pulling people out of my images for use on collages, etc.
And quite frankly. often my soccer and judo pictures of DS have horribly disctracting backgrounds. So usually, I just ignore all of that and extract the subject out of the photo so that I can begin playing.
This is the general technique that I use. There are a LOT of methods and a lot of tools available for you to use - this is just one way and I've found it works fairly well for me MOST of the time.
My primary tool for this procedure is the magnetic lasso tool, which is found underneath the lasso tool on your photoshop tool menu bar.
Now ... down to business ...
First, open the image you want to extract and make a copy of your background (I never work on the "original):
Next, using the magnetic lasso tool, draw a rough outline around the part of the image you want to select. I find this tool does a better than average job of getting the bulk of what I want selected.
Now it's time to clean up your selection - remove areas you don't need, add a few that got left out (I find this happens a lot around hands, feet, and ears). To add to your selection, hold down the shift key as you use your lasso tool. To remove from the selection, hold down the alt key. I use the magnifier to get in really close and make sure I have everything I want and nothing extra.
Now you have the bulk of what you need to get rid of all that clutter, but it helps to clean up the extraction a tiny bit more.
I do this using the modify options on the selection menu.
I first contract a few pixels (the number depends on the size of my original image. This example is a fairly small file, so I would contract 2 pixels. Then I smooth 2 pixels. And finally feather 4 pixels. I use roughly the same ratio (1:1:2) each time. But the actual number of pixels depends on the size of the original image.
The next step is to remove everything but your selection. To do this, I inverse my selection and then delete out the unwanted parts. So that you can see what I have done, for this example, I am sticking a layer underneath the copy of my background layer (where I've been working) that will just be filled with a solid color (red here).
Now you have your extracted image. And IMHO, this is where the fun begins. Now you can start combining images, backgrounds, text and such to create something special.
I hope this answers some of the questions I've been asked. Feel free to let me know if there is anything else ... if I have not covered something or if I have not given enough detail. This was put together pretty quickly.