Metrics for buying and managing Multi-Family Buildings

[Brian Noel]

Does anyone have any good metrics that i can get/ use for Multi-Family Buildings. I need to understand what are the typical percentages that should be allowed for Reserves, Taxes, Vacancies, Maint & Repairs, Prop Management, other operating expenses.  What is a good rule of thumb for all in Op Expenses before you determine your Net Cashflow ?  Thanks, Brian