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?
The average affiliate program will pay commissions in the 10-30% of the sale range depending on your margins. Affiliates are concerned with the commissions, but are also concerned with how well your website will convert the traffic that affiliates send to it. If you have a strong conversion rate and a good commission rate, that is usually a good formula for a well-performing affiliate channel.
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.