1. Use an online portal for maintenance requests and communication like apartments use. Apartments.com is the one that I use.
2. Read your lease thoroughly and update it with everything you are experiencing with this Tenant. Be sure to investigate local landlord-tenant laws.
3. Review local landlord and tenant laws to discover which maintenance requests are considered urgent, non-urgent, or can wait.
4. Get a Google voice number and establish an auto-reply. This will avoid you from being reached directly and lets the tenant know that you will review it ASAP.
5. Update your lease by extracting some terms and conditions from other apartment leases, lease share here on Bp or etc. that are found online.
6. Never tell your tenants that you are abroad or out of state. I manage from abroad and have found that some tenants use this as leverage.
7. Avoid doing 2-year leases. This decreases suffering from business relationships that are not favorable.
8. Create a Maintenance Responsibility Addendum that lists items such as the irrigation systems, HVAC upkeep and filters, plumbing, electrical, and appliances. Balance risk vs reward on this one.
These are some of the lessons I learned from managing abroad or long distance.