As a new landlord you definitely should consult a lawyer conversant in the Ontario Landlord and Tenant Act and the Residential Tenancies Act and the responsibilities of the Landlord. Presumably when you built that apartment you checked municipal laws and codes. If not, you must before you take a tenant, and make any changes to make it a legal apartment. The codes that apply have been formulated to ensure the safety and comfort of the tenant and others living in the building.
There are tenant and landlord rights and responsibilities under the Ontario Landlord and Tenant Act and the Residential Tenancies Act. There are municipal laws governing your apartment (or house) on offer.
Property Rental Laws define responsibilities pertaining to residential rental property management.
Your lawyer can help you craft a Tenancy Agreement to meet your specific needs and define clear expectations to protect both parties.
Your lawyer can help you determine if the prospective tenant is a “good risk.
Your lawyer can provide advice on ongoing landlord tenant relations and issues.