Sure! First I created new layer. Then on that layer, I created a mask, using the shape of the rocket. The mask made sure I wouldn't be able to color outside the rocket's shape. Then on that masked layer, I was able to use a very large, low opacity brush set to Overlay mode to paint some shine on the rocket. Because of the mask, I didn't need to worry about "coloring outside the lines".

Using brush modes is a great way to create some interesting color effects. I use Overlay mode sometimes (like above), but my favorite is Screen mode, which is fantastic for building up sharper highlights.

"I also put some shine to the rocket, again using a masked layer to keep the edges crisp even while using huge Overlay strokes"

I'm not getting what you did with masks.

Bye!
Carlo Valente