I've been doing a little bit of spritework recently; the palette is already organized for doing lighting effect gradients, so I really like using it for that. Pick one or two parts of the sprite to be light sources and have a bit of a gradient outward from those, and pick a direction for 'off-camera' lighting to give some depth to the flatter parts.
I like making a few small parts for guns like grips, stocks, barrels, etc. and copy-pasting the ones I like with filler to make larger guns. Personally, I also like using a very dark shade to outline a part, then do lighting to fill the inside of it. Here's the latest thing I've been working on:
Edit: A little more specific to your lasers - perhaps have a bit more of a dynamic range in the red parts, a larger gradient between light and dark?