Each object intended for extraction or isolation will suggest what techniques & tools should be used. The trick is to learn a bit about all of them so that you can look at an image and make a quick determination about which technique or combination of them will work most efficiently.
There are many ways to do this, and there are threads here about it, if you’ll only look through the thread titles a bit.
Google is also your best pal when you want to know how to do something. Use the following format to enter your search termsphotoshop tutorial|technique *terms for technique go here*The —> | <— character acts as a Boolean "or" operator in Google searching.
Here’s a compendium of links to get you started.
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http://www.adobeforums.com/cgi-bin/webx?128@@.3bb80e5d>
Click the link.
Bookmark it.
Start reading and follow through to tutorials.
Work the tutorials.
???
Profit!
🙂