Time Traveler's Guide to Not Messing Up the Timeline | Section 1: The Basics

Step 1: Don't Touch Anything.

Seriously, just stand there, don't move, and for the love of all that is temporal, do not, I repeat, DO NOT, interact with anything in this era.

This will prevent any unfortunate changes to the timeline, such as:

Preventing the invention of the toilet paper roll
Ensuring the Berlin Wall stays up for another 28 years
Allowing the invention of the selfie stick to happen exactly 10 years earlier than it did

Remember: time travel is like cooking a soufflé. You have to do it just right, or everything goes terribly wrong.