Images and illustrations can make or break a datasheet. A large number of readers recommend showing a professionally-taken photograph of the product actually installed and working, to give context as well as provide reassurance that it actually exists. While that’s great in theory, as another reader said: “We more often than not just receive a still from an engineer’s smartphone”, so you might need a Photoshop expert to retrieve the situation. Sadly, the quality of modern cameras does not make up for not having any photographic skill (or proper lighting), and saving a couple of hundred pounds by not commissioning a good local photographer can be a false economy.
A separate product shot can be used to illustrate key features with labels.
Line drawings should be clean and clear – keep the graphic designers away from these – and remember that the dimensions need to conform to the market. If there are downloadable 3D CAD models or DXF drawings, naturally it’s a good idea to link to them; as I’ve mentioned previously, a simple, understandable link to a web page listing the files available is the most flexible approach. The more links you allow out into the wild, the more you have to maintain in the future. If you do have a good 3D CAD model of the product, it might be worth investigating whether a rendered photorealistic image can be created if there’s no great photograph available.