Many of your photos suffer from slow shutter speeds, sometimes it may be deliberate creating motion effects, but mostly I guess that was not your intention.
You should try and get closer to the stage, use shorter focal length.
Halving the focal length will reduce image motion blur by 2 as well.
My biggest comment is on your compositions, although I'm not an expert myself
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Perhaps, try a different position; get yourself lower and/or than the subjects.
Try not always to centre the subject, create some room / space in the frames.
Find colours, often on stage people use different coloured lights, that creates nice coloured highlights and shadows.