On-Page Link Structuring is a complex SEO topic with a variety of opinions covering how frequently you should link to external vs internal pages, and in which cases to use nofollow links. We provide an informational breakdown on on the page's links for your review.
Some general principles in regards to link structuring include having a strong proportion of your links being to internal pages, as well as explicitly using 'Nofollow' links for any external links that may be to lower quality sites where you don't intend to pass value.