I don't think that you will find a single answer to this question. Lighting is probably the biggest challenge and it is also a full time job.

What I recommend is to to use small resolutions (50% of 960x540) and low samples (e.g. 50 or 100) for testing. You can also untick the Denoiser checkbox. Each test will only cost a couple of cents.

If you don't know much about lighting, just go for an HDRI. Do not hesitate to change the default image which is studio like for something else.
If you don't want a transparent background, it is also great to set the dispersion to 0.01.

For your final image. Increase the resolution, Change the samples to 350, Ensure that Cycles Denoiser is selected and active, Check the Full Global Illumination checkbox, Change randomize setting to 10%. Scratches, Dents, fingerprints, Dirt, Colour shift shall be kept below 20%. Deformation can be set to 80 to 100%.

Depth of Field is also great. Use the picker to select the part to focus on in your scene. Then generally set the radius to a value between 3 and 1mm.

Possibilities are endless.

Thanks so much, that will be really helpful for all of my renders and will save me a lot of money.

This may be a little of topic, I know money have different value for different people but if you compare what a Mecabricks render cost (I'd say an average between $0.1-0.5) and what a decent computer with hardware to render cost, you'll get quite many Mecabricks renders for that money. And remember that nothing is for free in the world, someone is always paying for it even if it's not you. In this case with Mecabricks free renders, it's Scrubs that pays for them, he bought all hardware and the renderfram is located in his house, so he pays the electricity bill. I don't think he is overpricing the paid renders, I'd say it's more the other way. 😃

Instead of seeing it as "wasting" your money on test renders, see it as a way to contribute to keep the farm alive and motivate Scrubs to continue with his masterpice of work that he has built. The time and money he is spending on this is more than anyone can imagine...

Great Point Sealund, Can you recommend colour balance. I was playing around with my compositing and now I can't render a normal image. When I change the values it doesn't reflect in the preview, only in the final render and it always turns out shocking. Please help