Our best advice here would be to talk to an SEO expert to get their opinion. That being said, a good general rule of thumb is to check your website’s domain authority using the Moz toolbar.
In most cases, if your site’s authority is less than 40, you should focus on the Authority side of SEO (i.e. getting more reputable websites to link to you). If your site’s authority is greater than 70, focus on the Relevancy side of SEO (setting up a proper SEO foundation).
If your site falls somewhere in the middle, then do a search for 5 of your biggest competitors, and compare your domain authority to theirs. If your domain authority is higher than theirs, then it’s probably best to focus on Relevancy. If your domain authority is lower than theirs, then it’s probably best to focus on Authority.