Some students are prone to making small calculation errors. Not errors in understanding, but errors like adding or multiplying integers incorrectly, or dropping a negative sign. Unsystematic errors in the terminology referenced here. Sometimes there's an obvious cause to this, like if the student writes sloppily and literally loses negative signs in their calculations or can't read their own handwriting, or if they're rushing through the calculation.
But suppose I've got a student who writes neatly and performs calculations carefully and methodically, but still makes a ton of small errors. How do I coach this student? "You need more practice" is probably true, but can't I be more helpful than that?