Depends on the subject being cut out and style of photography as to what techinque is best. I'm assuming you will be using a white background. If you have a hard edged subject like a packaging box, using the wand tool is usually fairly accurate. Click on the white background, and the tool should select your subject, this can be fine tuned by changing the tolerance in the options bar. The wands selection can also be added to or trimmed back, holding down shift and clicking adds to the selection, holding down alt, or option on a mac subtracts from your selection. You can also change to the lasso tool to add or subtract messy areas where there are lots of little parts selected that you either want or dont.
I usually start with the wand to make a quick selection, then switch to Quick Mask Mode, then I refine my selection, using the brush tool at various settings, using a softer brush where the edge of the subject is blurred or you want to include shadows.
You can also cut objects out fairly quickly using Paths, however I still find myself in Quick Mask Mode afterwards anyway. Paths have their advantages because you can save the cut out subject and its associated path as a file, for use in graphic design later on where you want a transparent background.
Hope this info is of use and you understand the techniques, with time you will become very proficient and fast at cutting out objects.
The following product was shot using a white backdrop, cut out then placed into a new document using a white background.
First of all use the crop tool on the original image to define the size of the subject in the final image. The Wand Tool will cut out the above product with ease as it has a hard edge, you can then go up top to "Select" then choose "Feather", experiment with this amount depending on image size and subject edge hardness. Then switch to Quick Mask Mode and using a soft brush, include any shadows that you may want.
Once you are happy with your selection, exit Quick Mask Mode and you will have a line of marching ants around your selection. If you are going to be making a small image out of this, then go up to "Select" and hit "Save Selection", give your selection a brief name, I just use 3 letters.
Then Go up to "Image" and "Resize". Resize the image to the final output size, once this is done, go back up to "Select", and choose "Load Selection", choose your selection form the drop down box. Then go up to "Edit" and choose "Copy", now open up a new document and input settings for this, change the document size to match that of your subject, this also depends on how tightly you have cropped it and how big you want your subject to be in the new document.
Once you have the new document open, go up to "Edit" and "Paste", your subject will appear as a layer, and you are free to move it about. From here you can adjust the image to suit.
This sounds like a long process, but it doesnt take that long, use the keyboard to speed it up, and also if you have many subjects that all need the same process, set up some actions that only require a simple press of a key to achieve a string of events.