The importance of keeping records cannot be over-emphasized, particularly for three reasons:
For Contract Purposes - keeping records of the problems that employees bring may show you a pattern of contract language that is perhaps unclear, or management may be interpreting it in a fashion that is adverse to the employees. By keeping "tabs" the steward can ensure that this problem is brought up in the next negotiations.
For Grievance Purposes - keeping records may assist you in tracking acts of harassment or discrimination by certain supervisors or in ensuring equal discipline for all employees.
For Duty of Fair Representation Purposes - by keeping records of contracts and discussions with employees, noting the names, dates and subject matter, you will be able to defend yourself if you are ever accused of failing to act on behalf of an employee.