Full contact details for both the landlord and the tenant to enable quick and easy communication plus preferred method of contact and even contact times.
A clear understanding as to when a landlord can visit and inspect the property and how much notice they must give the tenant.
A clear understanding on the part of the tenant that the landlord is entitled to inspect at reasonable times and with reasonable frequency.
A clear understanding on both sides as to what ‘quiet enjoyment’ of the property means [and express this in clear English in the Tenancy Agreement!].
Prevention is better than cure – both landlord and tenant should be encouraged to speak to each other if there is a concern or problem and do so at the earliest opportunity to avoid potential problems turning into real problems and issues.