If you're a fan of Google Inbox but sometimes mistakenly go to Gmail instead (whether through clicking on a Gmail link or bookmark), you can turn on a setting that will automatically redirect you to Inbox.
To get to that redirect setting, log into Inbox on your computer and click on the main menu at the top left. Scroll to the bottom to choose Settings, then in the Other section, check the box for "Redirect Gmail to inbox.google.com."
Then, when you visit gmail.com or mail.google.com, you'll be taken to inbox.google.com instead.
You can still access Gmail by going to Inbox, opening the main menu, and scrolling to the bottom to choose "Go to Gmail." If you want to turn off the redirect, head to the setting and simply uncheck the box.