Top 5 Beginner Tips to Get Your Renders Closer to Realism
When Rendering Product Shots these Top 5 Tips will Improve your renders:
1. Avoid Sharp Edges
When 3D modelling always make sure you use fillets or chamfers on any sharp edges. This will drastically improve your renders as these fillets and chamfers will reflect the light within your scene giving the 3D object some nice highlights which will contribute to the realism you are looking to achieve. Some render engines do have shaders that can add the fillets for you.
Scale plays an important factor when trying to render photo-realism so whatever you decide to model make sure that the proportions are as close to the real thing otherwise your lighting and materials might suffer making your rendered images look unrealistic.
No matter how good your materials and Lighting is it wont be enough to render photorealism. Every bit of detail you add to your model will more likely trick the eye into looking twice at the renders due to it being more believable.
Most rendering packages come with a default material library which consists of a range of material categories (Metals, Plastics, Glass etc). From experience use these materials as a starting point to give you a base material that you can tweak to add the final details (scratches, bumps, dust etc).
Use reference photographs of the material you are re-creating to see how reflective it is or if the surface is bumpy or rough.
You can buy some really great material packs online that have incorporated the fine details that give realism. These do come at a cost but from experience they are worth every penny!
For example here is a Material Pack I purchased for MODO that was created by Richard Yot - 160 Materials for $25 OMG!!
As for lighting I would recommend using HDRI Maps to light your scene especially when rendering product shots. if you can afford it I would recommend HDRI Light Studio OR you can find many free HDRI Map packs online like these: Collection of HDRI Map Packs as a cheaper option.