If you find yourself navigating from written instructions (either received in email, or given on paper) then a simple tip is to take a photograph of the email (or paper) and set it as the image on the lock screen.
Then when you are walking around there's no need to unlock your phone to read the directions.
Here, for example, is how to do that on the iPhone. Suppose you've received directions in an email (if you have a paper set of directions then just photograph them and jump ahead).
First, take a snapshot of the email containing the directions. You can do that by clicking the power button and home button at the same time. A screen shot will appear in Photos.