Internal linking is important for search engine optimization (SEO), and this is also the main reason why you should start doing it.
Most of the time your front page is the most popular one and, therefore, it is also the page that has the best SEO metrics. This will be, most likely, the most shared page of your website too. Remember though, that this does not mean that your front page is necessarily the best ranking. There are tools available that you can use to check this; I'm most familiar with Majestic.
With inner linking, you want to spread the power to the other pages of your website. In most cases, this starts from the front page but, of course, this is not always the case. It is also good to keep in mind that, if you include external links on your page, you will be spreading the power away from your website. To avoid this, you can, of course, include the
rel="nofollow" tag in your hyperlink but, if we are now talking about the landing page of your site (front page), you could just not include an external link there in the first place. Besides the SEO defect, you're also re-directing users away from site, which simply does not make any sense.
Likewise, you can also spread the power back to your front page. This might be the case if, for example, one of your posts gets a lot of attention and gains a lot of natural referrals and shares. In this scenario, having the proper structure in place helps, as you can just include an internal link to your front page that then continues to spread the power to other pages.
You might think that you have inner linking sorted out, as you have the navigation bar on your site that links to the subpages already, but this is not really the case. Having a good navigation is, of course, important, as it provides the visitors with an easy way to navigate through your page but, SEO wise, it does not get you too far.
As you might be aware, your navigation is included in every page of your website, and it is always the same. Navigation is duplicate content and, therefore, does not really count it as inner linking. Nowadays search engines are pretty smart, so they are capable of spotting the navigation. This does not mean that you have to go crazy and create a unique navigation to every page, don't, leave it as it is and focus on creating inner links in the content of your page.
Good internal link will have a proper anchor text that explains what the user will find behind this link. Additionally, you can also include a title tag where you can provide additional information for the anchor text. Additional information, not a duplicate of your anchor text. There are argument is whether this is useful or not, but don't be too wary of including the title text.