For travelers: Guides to digital privacy (from WIRED)

Here's an article that WIRED first published in 2017 and updated a couple months ago: How to Enter the US With Your Digital Privacy Intact

• Phone home: "alert a lawyer or a loved one who can contact a lawyer before going through customs, and contact them again when you get out."
• Lock down devices:  "Encrypt your hard drive" and "turn your devices off before entering customs..."
• Keep passwords secret: "if you stand your ground and don't reveal passwords or PINs, you may be detained and your devices confiscated—even sent off to a forensic facility—but you'll eventually get through..."
• Minimize the data you carry: "set up travel devices that store the minimum of sensitive data."

That article links to The WIRED Guide to Protecting Yourself From Government Surveillance, which you may also consult. It talks about other topics, including location data.