Accuracy
Some aspects of your system really matter. Others can be abstracted safely away.
Precision
Does that last decimal place matter? Can it be trusted?
Physical Principles
Computation has become the third paradigm for scientific discovery, along with theory and experiment. Sound models depend on sound understanding of principles.
Mathematical Principles
Mathematics and statistics are the languages of computational modeling. A broad vocabulary in a wide variety of dialects is essential to being able to describe a system accurately.