If you can have a link to your site put on another website this may not only help with direct traffic from people clicking on the link but can also look good in the eyes of some of the search engines as it shows that other websites think the information on your site is important. Web marketing of this type should be analysed before you agree to pay for links on sites. If the site is very relevant, for example you may be offering hotel accommodation on a theme park website, then the chances are you will get people clicking through which in turn could convert to enquiries.
A good option to discuss with potential link partners is a trial period of say 3 months. You may agree a free trial or a special discounted price for this period to track how affective it is before you tie in to any long term commitment. Ensure you have adequate tracking software installed on your website to check the results and amount of visitors etc you have acquired from this link, do not just rely on the information provided by the link partner.