First,check out the newspapers for apartment information.If you're interested in an apartment,call the landlord or landlady to make an appointment to see it for yourself.
Sencond,when you get there,you can ask the owner all the information about the apartment,like how large is it,is central heating included,is the plumbing good,are the walls faulty etc.
Third,if you'd like to rent the apartment,be sure to reach an agreement with the owner on the rent.Don't forget to give the owner some deposits.