Keyshot Users

I'm still learning myself so don't want to give you wrong advice, but i'm finding youtube videos very helpful

Always make a specific model for rendering, i normally make two models, the first one for production, to make plans, etc., and the other one for rendering.

In the rendering model always put fillets on the edges of everything, because in reality all objects have fillets even microscopic ones, so in order to make your render look closer to reality, you may want to fillet the edges of everything, this will give your render more realism, it's going to have more reflexes on the edges and it will generally look better.

Late reply, but realism is achieved through mastering three things: modelling, materials and lighting.

Modelling: As Francisco mentioned, all objects have fillets. Keep that in mind while you're modelling for a render.

Materails: Likewise, no materials are perfect in reality. You always have imperfections present, which can be implemented through bump maps, textures, roughness, etc. in the material graph inside Keyshot.

Lighting: Realistic lighting is also key to photorealistic renders. Try to imagine how objects are lit up in the real world, and try to replicate that lighting in your renders.

Keyshots YouTube-channel is full of webinars. I'd suggest you to check out Esben Oxholm on YouTube as well!