Most pianos should be tuned at least once a year, to keep them well in tune. If a piano is required to be tuned and kept at concert pitch, twice yearly tunings are recommended, sometimes necessary.

The benefits of regular tuning are, the piano is always in tune and therefore always sounds nice, and it gives the tuner an opportunity to keep an eye on the rest of the piano and report to the customer should attention be required elsewhere. Sometimes, a few pounds spent early on, to cure a minor fault, is better than leaving it until further damge is done, resulting in a much larger repair bill. So, regular tuning can actually save money in the long term.

The piano owner can do much themselves to ensure the well being of their instrument.

Keeping the temperature and humidity as constant as possible, and not too extreme, is very beneficial to any piano, but especially older ones, built before the days of central heating. For an average room temperature of 65f - 75f, the relative humidity should be between 50% - 70%, the ideal being around 65%. It is worth spending a few pounds on a good thermometer for the temperature, and a hygrometer for the humidity. Both can be bought fairly cheaply from most garden centres.

If the humidity is too low, a humidifier will cure the problem, although the simple expedient of a couple of large pot plants in the same room will often do the trick. Or, a couple of large ceramic plant pot saucers, filled with decorative gravel and kept topped with water will work just as well. Incidentally,the old trick of a jam jar full of water in the bottom of the piano is NOT a good idea. Firstly, it can cause localised rusting at the bottom end of the piano strings, and secondly, because it is out of sight, people tend to forget about it. Consequently, the water soon evaporates, the jar is dry, and the whole point of the excercise is lost. In any case, if the room air is generally dry, the jam jar treatment just doesn't work, the water simply evaporating into the room. Far better to humidify the whole room. Much healthier for human beings too. 

The consequences of too dry an atmosphere are loose tuning pins, which can be very expensive to put right, loose action parts, and in the case of old pianos, lifting veneer on the case. 

Conversely, if the temperature is too cold, and the air too damp, steps should be taken to rectify this too. Dehumidifiers to correct the humidity, and a gentle background heat go a long way. Although, pianos tend to survive better in these conditions than if too warm and dry.

The worst results of these conditions being rust forming on the strings, and stiff hammers and dampers. Keeping  pianos out of direct sunlight and draughts is a big help too. Try to keep the top lid slightly open on it's prop stick if one is available. This helps keep the piano aired. Regular playing discourages moths. And try not to stand pot plants on the top. Water running down inside can cause untold damage, and water marks are difficult to get rid of.