I like this style, it looks really simple, but still nice to look at

As for advice, maybe add a few filters to the aura, and make Goku’s poses more dramatic

Like, instead of making his arms go in a sort of flexing position, make him throw them all the way to his sides, fully extended and reaching behind him a little. Or, you could make it look like he’s really fighting against the force of the Kamehameha thats pushing him back instead of it just kinda pushing him a bit.