"If it's not on your list, it shouldn't be in your bag," advises Dyment of OneBag.com. "What happens with people is that they pack before their trip, and that packing activity consists mostly of talking to yourself and saying, 'Well I might need this and I might need that and what if the queen invites me to dinner?' And that's death to light packing."
Dyment has two big tricks for packing a bag correctly: Don't let any space go unused, and wrap your clothes in bundles.
"If you're packing a pair of running shoes, say, don't forget there's a lot of space inside those shoes that you can use to pack stuff," he says.
When it comes to clothing, Dyment says travelers who fold items individually, put them in a stack and force them in the suitcase are making a huge mistake.
Instead, he suggests using a technique called bundle wrapping, because it keeps clothes from getting wrinkled and takes up less space.
"You think of laying a shirt flat on your bed and placing this bundle where the chest would go and then gently wrap the sleeves around the bundle, and then bring the bottom up and wrap it around the top," he says.
More tips and the audio interview from NPR radio here.