The user stories must follow the INVEST rules:
I – Independent (can be moved from one time frame to another) N – Negotiable (can be modified a little, define global details come later) V – Valuable (important task for the customer) E – Estimable (x points fotr that and Y for another one) S – Small T – Testable (can make test only affecting these part)
SMART tasks
S – Specific M – Measurable A – Achievable R – Relevant T – Time-boxed