I talked a bit about choosing PNGs for your manip covers. Let's discuss more about what a PNG image is.

A PNG file is a file with a transparent background, sometimes they're simply called a transparency. Not all PNG files have a transparent background but it is the only file extension I'm aware of that can be saved without a background.

It takes practice and work to cut a PNG. You need to make certain you don't cut out anything important to the image. Round edges must be traced carefully so it doesn't look as if you took an ax to them. You can use the magic wand tool (which isn't very magical in most cases) but it tends to remove a lot more than you intended.

The magic wand tool works by picking pixels of a similar color to the area you clicked on, which is why it ends up being so inaccurate. If your background is white and your model's shirt is gray, you'll likely lose any part of the shirt that appears closer to white than gray. It can also leave behind specks where the wand didn't pick up on pixels. A lot of designers use Photoshop to cut PNGs. I use GIMP because I find it easier to use. The lasso tool in Gimp allows you to drop 'dots' that can be picked up and moved to adjust where they landed. It makes cutting rounded edges a lot easier.

Let's show an example of how the magic wand tool can go astray.

This is the original image

And here is how the magic wand tool cut it out 

Granted this is an extreme example, but you get the point. Just clicking on the background with the magic wand tool might be easier but it doesn't give you a perfectly cut out PNG. You'll notice there's still gray left in and around her hair. 

Here is the manually cut version of the PNG

The edges end up much cleaner and she still has a torso. You do lose the little wispy pieces of hair because it's simply too difficult to cut them out without having them appear awkward. But it's a cleaner cut image when you do it manually and this allows you to create more stunning covers.

If you don't have the ability to cut your own PNGs then you probably Google until you find what you need. Sadly, there are a lot of lazy PNG cutters out there. They'll cut the image out of the background, but they won't do the detail work to complete the look. 

This would be an example of a lazy cut. The fine details inside the key still have the background. Lazy cutters don't want to take the time to do the details.  

This is the same image with the details cut out

To cut out the tiny details I often will make the image larger by increasing the preview percentage in the program. I don't change the actual image size. It always helps if your images are high quality and large even if you're going to be using it on something smaller. It's easier to cut because you can increase size without the images going fuzzy and making details hard to pick out. It's always easier to make an image smaller than it is to make it bigger.

As I said, I use Gimp to cut my PNGs because you can drop dots with the Lasso tool and move them around

This is a screenshot of the Gimp "drop dots"  (you'll also notice at the bottom in the left corner that I have the image set to 400% so I can see the smaller details) 

Cutting PNGs requires a lot of patience and attention to detail. It has taken me a while to get it right and now I can usually cut them pretty quickly, depending on the amount of details in the image. Since I've learned to cut PNGs I've done almost two thousand of them. If you need a PNG I probably have it lol. 

I've seen designers mention using a background-removing tool or app, these are very similar to the magic wand tool. They pick out pixels of similar colors and erase them. It can cause you to lose things you don't want to be cut out of the image.