How to achieve the Very white non wrinkle no seamed look?

Do you use seamless paper as a backdrop, or do you just take care of the background later in photo shop. (If you photoshop it, how do you do it )
Thanks so much for your help. This has been driving me maddd

There are many ways to do it. I like seamless paper but I also have at least 100 canvas backgrounds as well.

1) don't have wrinkles get a steamer
2) lighting the background the right way.
3) move subject away from background so you can over expose (blow out) the white background and keep it out of focus. This also helps with shadows.
4) seamless paper works very good
5) You can also do in photoshop (I would try to get it right in camera though) try select by color range (it helps if the subject is not the same color as your background too.)

If you would like to post an image I can take a look at it and show you where your having troubles

Everything Stari said about getting it right in-camera is right on.

However, if you still see wrinkles in postprocessing, you can "smooth" an area by cloning (with a softened edge brush) a fairly wrinkle-free spot, then cloning that larger area until you've got a smooth background. You can smooth that cloned area even more with the blurring tool. You'll have to be pretty precise and careful (using a harder brush) as you get closer to your foreground subject.