How many outbound links to stay safe?

For example; if your website pr has 1, so you should try to put those website link on your website who have pr 2 or more. When you follow this thing in your website so your visitors and crawler also can impress by visiting and crawling your website, be sure about these all link should be relevant to your services or products.

 

I read somewhere, can not remember where - but a case study was done, and sites with 15 outgoing links ranked higher than others. Not sure about the accuracy, because I can not remember where I read it.

 

U might get a penalty for having that many sitewide outbound links. Especially if they are not all related.

 

why link selling is not good for our website, like we are doing link exchange then what will be the effect on our website?

 

Selling many links is not good for any website. there is have limitation about outbound links. if your website have many different niche outbound links so you can get banned by google.
In link exchange you created links page and then you exchange links with others. means that you are not place other website links on your home page.
so means that its not get bad effect for website with your are doing exchange link with only relevant websites.