Start with the evidence
For each figure, record its source and whether it is verified, estimated or still missing. Request current leases, a rent roll, available payment records, property-tax bills, utility costs, insurance information and maintenance history. Obtain your own insurance and financing estimates rather than assuming the seller's costs will carry over.
Keep existing rent separate from projected rent after turnover or improvements. A higher advertised rent does not establish what can lawfully be charged to an existing tenant. Have tenancy questions reviewed before using a different rent in your purchase budget.
