Internet
The apartments that can be found here are likely to be the ones not rent controlled. They often prove not to provide any surprises concerning their state of construction or interior. There are plenty of websites covering rentals in Prague but only a few deal with other regions of the Czech Republic as well.
Newspapers
Almost all of the major national and local newspapers in the Czech Republic have rental offers in their classifieds sections. Rent controlled accommodations may be found here as well.
People you know
Since many privately rented properties are not advertised, you need to tell everyone you come in contact with that you are looking for a place to live. If you get a referral through someone you know, there will be a personal link and better chances that you are treated more fairly.
Your employer
If you are coming to the Czech Republic with a job offer, it’s a wise move to get your employer to assist in finding a flat. This is a good way to get a decent flat from a landlord who might be more trustworthy than average. Most employers will consider helping a foreign employee out when it comes to finding somewhere to live. Don’t hesitate to ask.
Notice boards
In most cities and towns there are community notice boards where it is either free or very cheap to put up an ad (these avoid the cost of putting a classified ad in a newspaper).
Place your own ads
Put up an ad for what you are looking for. Make sure you list your requirements exactly. Although this may appear to be an unlikely way to find a flat, it seems to work very well in the Czech Republic. There are many landlords looking to rent out without having to deal with agencies.