I am planning to start/join affiliate program but not sure how should i go about. I am not sure how much percentage of affiliate sharing is profitable?
It really is all about your cost and margins; How much margin do you have on your products and services to account for a commission and how will that cost structure play into your marketing budget month to month.
Unfortunately, the only one who can answer that is you. I always recommend to start out at a lower, conservative commission structure to test. If things work out, you can always increase the commission rate to make it more competitive and enticing for affiliates.
I run through this scenario as I see it a lot with clients in my post here: http://upfoundry.com/guides/2016/02/how-to-set-your-commission-ratestructure-for-affiliates/
If you find it helpful and have more questions - don't hesitate to request a call.