Length. Avoid over long title tags. They hog too much real estate in social shares.

Indexed length. At the same time, keep in mind that while Google may not display more than 65 characters, they index title tags of any length (within reason). Therefore, un-displayed title tag text can still influence how Google ranks a particular page.

Brevity. It’s OK to use fewer than 65 characters, but make sure you give Google and humans enough information to grasp the essence of what the page’s content is all about.

Consistent style. For websites especially, you make the best impression on users when title tags are styled consistently. If, for instance, you use sentence case here and title case there, you’ll give users the impression that your site is haphazard and unsophisticated. This impression will quickly extend to your business.

Remain relevant. By all means update your site’s title tags as your keyword strategy changes. However, be sure to update page content as well, in order to keep it fully relevant to the new tag.