The lessee must keep the property well maintained, not damage it in any way nor disturb the neighbours by having loud parties, deafening music or carrying out prohibited activities. The contract usually stipulates that the property must be used exclusively as a place in which to live, not to run a business, unless specified otherwise by both contracting parties.
If the property has a telephone, the landlord usually demands a special deposit for its use and determines whether he'll allow international calls or have them blocked. This is a precautionary measure the landlord takes because sometimes when the phone bill arrives, the lessee has already left and there is no way of collecting other than taking it out of the guarantee deposit. A good tenant can live a very peaceful, unmolested life and allow the landlord to live peacefully too provided he complies with the provisions contained in the contract.
As a landlord, my family has had families occupying some of our apartments for more than 20 years. We never pester them with frequent visits nor mess with their private lives. If you decide to rent, not buy a property, I'm sure you'll assure yourself peaceful living and good relations with the property owner by being a good tenant. That holds true whether you're in Costa Rica or elsewhere.
In time, if you've decided you want to live permanently in the country and prefer to own rather than rent, you should consider carefully whether the way to go is to build your own or buy an existing property whether it's a house or a condominium. Both have their advantages and disadvantages. You alone and your spouse are the only ones that can decide whether to locate in the city, on the suburbs, in the country, near the beach or up in the mountains. And how much you can and want to spend to live in your own property. In looking for a good lot in which to build or an existing property to purchase, it's advisable to enlist the assistance of a reliable bi-lingual real estate broker to help you in your search.
In recent years many luxurious condominiums have been built around San José and some retirees, especially those who are financially better off, have preferred them over a house. Maintenance and security costs make living in them much higher, but this is no obstacle for those who can afford the added expense.
After housing, the biggest cost of living in Costa Rica is food and you'll benefit by doing what the locals do. Of course, if you want to always eat imported foods, you'll have to pay their high price. The best prices for staple items are found in the supermarkets while fruits and vegetables have their lowest prices at the ferias del agricultor or outdoor farmers markets held on Saturday or Sunday mornings depending on the locality. Most of the towns and larger villages have them. These ferias bypass the distributor or reseller and bring together the farmer and the consumer. Here you can touch and even squeeze the fruit to personally judge the degree of ripeness without being insulted as I was a few years ago when I squeezed a plum at a fruit stand on Canal Street in New Orleans.