If it's been more than a year since your piano was tuned, it will probably require a "pitch raise". This means that the piano's strings need to be pulled up to proper tension/pitch. Pitch raising a piano is not the same as tuning a piano, here's why:
Piano strings are strung over a wooden, flexible soundboard and over a cast iron, arguably movable plate. When one string is "tightened up" to where it should be, this creates tension on the soundboard and plate. When the next string is "tightened" it adds even more tension to the soundboard and plate--BUT, it also relieves some of the tension of the previous string. Therefore, by the time that one has finished pitch raising a piano, certain strings will be out of tune again! The idea of pitch raising is to get the piano close to in-tune, then go through again and actually tune the instrument.
There are certain risks involved when pitch raising. Often, brittle or rusty strings can break as a result of the newly added tension. Pitch raising also creates instability--the piano will go out of tune shortly afterwards. This is due to a number of factors: the soundboard and plate will take time to adjust to the newly added tension, and once they settle the strings will have changed from where they were set by the piano technician. Tuning pins that have been moved, twisted and torqued "have memory" and will want to return to their original positions.
Therefore, the less movement of the tuning pins and strings the better! Essentially, a piano that is already close to in tune will be the easiest to tune!
Often times, neglected pianos will be dirty, grimy and dusty. Dusting and vacuuming them out is recommended so that all parts can move freely and so that no buzzing will be a result of uncleanliness.
Many pianos will have sticky keys, a loose glue joint that causes clicking, or loose screws that needs to be tightened. All of these are things that I can fix when I visit you and your piano. Usually when going to a client's I evaluate their piano and then discuss what its needs are with them. Every piano is unique! Every one has its good and bad qualities, and I'll work with it all in order to get the best sound out of your piano!