One thing that can trip us all up from time to time is directional lighting. It’s easy when everything is lit from above but sometimes this just doesn’t do a figure justice and this is where it can get complicated. As you paint the model it can become difficult to gauge exactly where the light is coming from. This can make determining highlights and shadows difficult and mistakes may not be seen until it’s too late.
One solution to this is to take a reference photo of the figure and keep it to hand whilst you paint.
Sometimes it is better to wait until the figure has been undercoated (Gray works best for this) as this will prevent to many bright highlights on metal minis (not such a problem with plastic). Then set your model up with a strong light source where you want the light be come from (strong enough to create strong highlights and shadows but not enough to white out your camera contrast). Now take a few reference photos from different angles, these will be your guide to where the highlights and shadows should be on your model as you paint. If shadows and highlights are still not clear from your photos try adjusting the contrast in an image editing program.