Unfortunately, what you are looking for has no single nor quick solution (assuming you want quality results). There are many ways to achieve this, so that is why you see different techniques. You could use QuickMask, or Select->Color Range, or use different channels, or third party apps such as KnockOut, or Image->Extract, or…
There are plenty of tutorials out there, just find the one that best fits your image (since many of the techniques are useful for certain types of extraction) and also make sure they are for the version of PS you have (or close to it) since some techniques are now outdated.
Pauley