There are some points to consider when establishing entry and exit links on websites. Topic of a website is important when linking to any website from your site. If the website that you link has the same content as your website, this will benefit you in terms of Optimization and PageRank. But if you add websites with different content to your site, your PageRank value may decrease. For instance, let's say that your website is a flash game site. If your exit link is a website that promotes games, it means that you have the same content and it will be useful. In contrast, if the site that you are linking is a movie site, then your content will not match.
Link transaction between two sites with same content will be very beneficial for both in terms of SEO and PageRank.
If a recently opened website has a fast kind of entry and exit, then it will receive penalty by being put into the SandBox. When you get backlink from a website that have same target keywords, your website's ranking will be higher in that search as well.
Google realizes that it is an artificial SEO improvement and therefore Google’s valuing to those websites reduce considerably. Therefore, it will be beneficial for you to do cross-link exchange in terms of SEO.
In addition, while it is said that link changes made with the websites on the same server are ignored by search engines, link exchanges on same server affects PageRank just like a website's PageRank improvement affects its subpages. But of course, it is more useful to make a cross-link exchange with a website on a different server.
Google also enjoys in-site linking. For example, when you install a similar post to your website or link to other articles and tags within your post, Google will like your site more.