BE AWARE! It is not safe to view the eclipse without proper eye protection, not even with very dark sunglasses. Doing so can cause permanent damage to your retina which may result in blindness.
When viewing the eclipse,
DO:
Wear glasses or use viewers which meet the international safety standard requirement of ISO 12312-2.
Learn how to recycle your paper eclipse viewing glasses: Earth 911 and Smithsonian.com
Also use protective filters for cameras and viewing through telescopes and binoculars (link here for information).
Use a pinhole projector instead of looking into the sky:
Click here to learn how to make one.
Click here to print one from the NASA Eclipse 2017 website.
DO NOT:
Use ordinary sunglasses, no matter how dark!!!
Use glasses or viewers which are damaged (are scratched, have holes, or are torn).
Article: "Why you absolutely cannot stare at the sun without eclipse glasses, explained" [Vox.com]
Credit: NASA Goddard Media Studios
Yet another way to make a pinhole projector.