I keep on getting a brownish-green hue around me
Lighting could definitely be part of the problem here. Typically, for green screen work, it helps to have a light between yourself and your green screen to get rid of those shadows behind you (sort of like a backlight).

To fix your current footage, I'd increase the sensitivity of your chroma key in After Effects, since it looks like AE is essentially leaving a thin outline of the screen around you. If you increase your tolerance, you should see that outline shrink a bit. Feathering the edges of your image can help with this, too.