Do Your Own Routine Inspections
Any successful property owner or manager will recommend doing routine inspections at least once a year. This enables you to ensure you are providing safe habitable conditions as required by law, catch maintenance issues before they devolve into expensive disasters, and identify any tenant compliance problems early. This practice also helps to establish a good rapport with tenants. If they see you on a regular (but not too annoyingly frequent) basis, they are more likely to care for your property and trust you to keep it well-maintained.
Create a checklist that reflects each of your properties (see the example below) and make sure to follow up. Also, take the opportunity to educate the tenant on any property care tasks they should be doing themselves.