Where you run matters as much as how far. The ground gives different feedback and different risks, and picking the right surface is one of the simplest ways to make the barefoot transition go well.
This is general information, not medical advice.
Smooth pavement
Asphalt and smooth concrete sound harsh, but they are some of the best places to learn. The surface is predictable, so nothing underfoot distracts you from your stride. You can keep your head up and focus on landing lightly and quickly.
Smooth pavement rewards good form and punishes pounding, which makes it an honest teacher.
Grass
Grass is soft and forgiving, easy on skin that is still toughening up. The catch is that it hides things: stones, holes, hard ruts. Use grass you know, and keep your eyes up rather than glued to the ground.
Sand
Firm, wet sand near the waterline is a pleasant, low-impact surface and a classic place to run barefoot. Loose, dry sand is a different story: it is tiring, shifts under you and works your calves hard, so keep those efforts short at first.
Trails and dirt
Packed dirt is a good middle ground. Rougher trails with rocks and roots are rewarding but demand tougher soles and better attention, so treat them as something to build up to, not a starting point.
The simple rule
Start on smooth, predictable surfaces, then add rougher ground as your feet adapt. Mixing surfaces over time builds resilient feet, but the order matters.
For the wider how-to, see barefoot running tips for beginners. If rough ground appeals, the right footwear helps, so read how to choose minimalist running shoes, and keep an eye on the warning signs in common barefoot running injuries.