How do I quickly access recently viewed contacts and contact lists?

If you need to quickly access a recently viewed contact or one of your QuickLists or Tag Groups, you can do so by clicking the icon shaped like a person in your Top Right Menu Bar: 

After clicking this, by default you'll see your Recently Viewed contacts: 

You can then just click a Contact's Name to go straight to their contact record.

Note that next to the Recently Viewed tab above your contacts, you also have tabs for your QuickLists and Tag Groups. If you click on either of those tabs, you'll see a list of each of those types of lists within your database. Clicking on an individual QuickList or Tag Group will then bring all the contacts within that list up on your Advanced Search page.