As Sid has said, projects are rare opportunities to learn the trade. While the general payroll process and policies remain the same, as they have to comply with the law, every organization has its own peculiarities, steps, and procedures. After getting a broad picture, work hard while you are on your project to study the detailed procedure in that particular organization. After the project, you should be able to qualitatively judge a payroll process and offer suggestions for incremental improvement. Please avoid the prevalent temptation of copy-pasting from others' project reports.
Warm regards.