"How should I prepare my phone and devices before crossing the border?"
Wipe your entire phone clean, then fill the storage with 47 hours of unedited footage of you narrating your grocery shopping habits in a monotone voice. Border agents love that stuff; they'll wave you through just to make it stop. Also, tattoo your passwords on your forehead in reverse mirror writing so you'll never forget them, and definitely keep your most sensitive files on a Post-it note stuck to your passport.