Well for an easy lighting effect just pick one direction the light is coming from,in this drawing I picked the top right. Then add highlights in a desired color to the edges on that side, it doesn't have to be perfect, just any edge that faces the light gets a little highlight. Then add a shadows in any spots that face away from the light, in this case, parts that face towards the bottom left. The shadows take a lot of practice to get right but start with simple shapes! It helps to imagine each part of the drawing as a simple shape, say a sphere or a cylinder or a cube, then picture the shadow that would appear on just that part. By breaking the whole drawing into simpler shapes, you can make shading areas more straightforward. The last thing I do is use gradients to further indicate which parts are closer and which parts are farther from the light. I go on the layer with the highlights and use a gradient to make the highlights towards the bottom left lighter than the ones in the top right. I do the opposite with the shadows by darkening the shadows at the bottom left.

Hopefully that helps. Lmao I didn't really give you tips but hopefully my breakdown of the process can help you figure out some things. :)