Lovely work, and great interpretation of a very bright, energetic song!
I haven't used medibang paint pro, but if that's a program that uses layers, I think you'd have a lot of fun with layer styles (like color dodge, linear dodge, or hard light) when painting stars, comets, and other glow effects. Really gives gives a nice kick to the contrast and a pop of colour!
Keep up the good work. Just going through the first of all of the contest entries now.