If I am about to as an Affiliate for Non-Digital Products. Then which affiliate networking site should I choose?
I think that's the best for you to go for is 'Amazon Affiliate Services'. They have plenty of non-digital products and as beginner you can do very well with their services.
I agree with Brian. Amazon is the best if you are selling non-digital products.
You can also contact individual marketers. There are not so many platforms for non-digital items.