I will have to cut out some people out of backgrounds. Apart from how to do it what are some tips and tricks that will make the result look better? (Like maybe using a feather etc,..?)
The most useful trick is to take the photo so that the background can be removed easily. There's plenty of material available how to do the shooting this way (= perfect sharpness, no noise due high ISO nor JPG compression, high contrasts but no under- & overexposure, uniform light, distant uniformly lighted & colored background with different color than the remaining foreground objects; distant background give less color contamination to the non-background parts)
If you have taken the photo well, you do like they do in videos, the only somehow tricky part is to refine edge if there's a large blown hair.
This is not always possible. For example I have removed people from photos after they had fallen from grace and the chief wanted them to be removed like they had never existed. The rest had to be placed onto a new background image so that there was no gaps.
Something to learn for non-easy cases:
1) to draw perfect clipping paths and to paint manually clipping masks; easy to use selection tools such as "select color range" and "the magic wand" do the trick rarely (except if the photo was taken specially for easy background removal)
2) to redraw hair
3) making local light and color adjustments; often the removed parts spread color or make shadow to the remaining parts. All these must be fixed because an effect without a cause looks out very disturbing.
4) how to suppress noise (if you cannot prevent it beforehand)
Do not waste your money to "magical one click background removal tools". They do their job as advertised only in well prepared cases. They can speed the process if you do the needed preparations for the shooting.
One 3rd party tool has been valuable, one which
- allows drawing clipping paths like one draws Bezier curves or works like a contrast or color edge following magnetic lasso tool, and there's one click switch between the modes in the middle of drawing a path
- accepts undos during drawing a path (=go back to the preceding node) without a must to start from the beginning
- easy zooming and panning during drawing
- allows insertions and subtractions from the selected area and the preview of the background removal before confirming it.
This one was Aerocut but the company has been sold. Unfortunately I do not know a full replacement for it.
ADD: In Photoshop one of the easy selection tools, namely the quick selection tool earns special attention. The tool seems to be underestimated. It uses some advanced math and it can learn where one wants the edge to be. Only select and deselect by changing between + and - modes at the same area. The tool often somehow calculates your will.
ADD2: There's several background removal web services. Many of them have been there a long time. They use human workers who do the job. When a worker do it day after day, he obviously develops his speed and accuracy to quite different level than one, who does this occasionally. Otherwise such services couldn't stay alive. I guess using a service pays well off when one is in a hurry.
Recently also automatic background removal services have appeared. I have not tried them, but here's an example to see: https://www.remove.bg