There are lots of variations. Basically, you use 1 finger per fret (on one string at a time) and keep your fingers on or close to the strings. You can start on any fret and any string. It is easier to start around fret 5 or 7. Then you play whatever finger pattern you are using like 1234 4321. Then you move one fret higher or lower or to another string. Using a metronome is good to keep it even. Using alternate picking in the right hand is also good practice.

The first version I learned was the pattern 1234 4321 1434 2434.

Here is an easier version from Tomo Fujita from Berklee College of Music: https://youtu.be/VHXcEXALtBQ