First, pick a picture with a strong difference between your focus and the background. The easiest ones will always be photo shoots with solid backgrounds.
Today I’m going to use this photo:
1) Open up your photo and select the Selection tool. Make sure it’s on plus.
2) Click and drag around your focal point until you have your background selected. Switch to the minus to remove parts if it selects too much.
3) Next, invert the selection.
4) Then add a vector mask by clicking the square with a circle in it.
Example: Your layer should look like this.
5) Double click the black and white box on your layer and this window will pop up.
6) Select the Refine Edge Brush Tool and make sure it’s on plus.
7) Zoom in and paint around the edges of the hair or finer details. If it adds too much, click the minus sign and repaint over the spot.
Example: The left half of her hair has been brushed over while the right side has not. You can notice a considerable difference bectween the hardness of the pixels. (also, feel free to adjust the Global Refinements/Edge Detection to your liking, just play around with the sliders and you’ll catch on quick!)
8) Click OK and review your image.
9) Reselect the black and white vector mask and change your PS colors to black and white. Using the brush tool, go in and paint back (or out) details. Or, use the Polygonal lasso tool to make a selection and fill it with black to remove or white to add. Here, I removed a section between her arm and her waist.
10) Finally, add a background color/pattern and add any psds/actions/etc.
Here’s the final product! Hope this helps!