I agree Clarabean. One way links from the websites which are not related to your field will not have a very good effect on your website rankings on search engines but if you have one way links from websites which belong to your field then it can have a good effect on your website rankings. Also, it depends on the
PR of the website from where you get your one way link. If the
PR of a website is good in comparison to your website
PR then you can also exchange link with it.