What's a town? Which town does a point belong to?
Now this is a difficult question since it depends on the local administrational structure and there simply is no universally useful definition. Learn about how the country is organized, and use your common sense.
Most countries have some kind of small(est) independent administrational unit, whatever it is called: municipality, commune, civil parish, township... there may be lots of names for lots of similar units and lots of places where they just depict something else. One of these will do. In many countries BCers before you have already chosen an administrational level to call a "city" in the BC database, and in most well-maintained countries these usually represent municipalities or similiar structure which are entirely legitimate to be called "towns" for this challenge.
However, there may be reasons why the "cities" in the BC database are not cities, towns or whatever you might call it, so better don't stick to them if they sound unreasonable. One example is that large cities like Paris, Wien, Berlin or London are often split into districts in the BC database which doesn't make the districts cities in real life. In many other countries the term "well-maintained" simply doesn't apply, because there is no region manager cleaning up the database regularily according to local conventions.
In some countries not every square metre of ground is assigned to a town. If you release in such an unincorporated area, you may assign them to nearby towns by some reasonable rule you'll have to find yourself, like going by the postcodes or simply using the closest one.
You also might need to find a map service which includes the borders between towns to find where a place belongs to. If you know a reliable service for a region, you're welcome to tell us.
I'll collect the links here:
Germany - http://www.stadtplandienst.de
Switzerland - http://www.stadtplandienst.ch
Austria - http://www.stadtplandienst.at
Three sections of the same commercial map service (but simple lookups are free of charge). They show municipality borders as various violet lines (they may be dotted) in the lowest three scales. Quite reliable and precise. Where borders changed during the past few years, often outdated, though.
Globally but incomplete - http://www.openstreetmap.org
Given the very nature of OSM, they show borders exactly where and like some volunteer added them. In some areas they could import government data. Quality ranges from "missing entirely" over "rough guess" to "perfectly to the point". Use your common sense to determine whether the lines you find are useful. Feel free to contribute yourself.
A final note...
This challenge is not a competition. We do count, we do set a goal, but we don't judge anyone by the numbers reached or not. Letting it discourage you if someone elses count is far above yours is just as wrong as feeling superior if yours is the larger one. No winner will be appointed on terms of numbers.
"Towns" vary heavily in size between regions. Visiting 52 of them may be a daytrip for some people but a lifetime challenge for others. It's not your fault if you are one of the latter because your municipalities are so large that there are only a few in reach. If you don't think you can visit so many towns, you are still welcome to just try and release in as many towns as possible. If you reach the 52 during the year, you are still welcome to continue and raise your own number to astronomical heights.
Now go and explore. A whole world of wonders and surprises is waiting for you, and your books will be some of them.