4. Refine your selection

Adjust your mask to remove any 'green screen fringe colour'.

Use an Adjustment Hue/Saturation Layer and adjust the Green Pixel colour to a more neutral colour that matches your scene better. Adjust the saturation (amount of colour) that are in the fringe pixels.

View MORE: Try this 4 minute video from a Master Photoshop Presenter on PixImperfect. This is a 4 minute tutorial (with audio) showing the same technique above with a bit more detail.