The Internet offers excellent resources for house-hunters. One of the largest local housing portals is Hemnet (only available in Swedish).
There are many websites dedicated to searching for accommodation that are available in English for example www.bostadsportal.se . You can also try www.uthyrningsportal.se which is especially interesting if you are looking for apartments in Stockholm, Göteborg or Malmö. Another alternative is a classifieds site called www.blocket.se , which at this time is only available in Swedish.
You can as well use housing sections on websites for Expats such as www.justlanded.com or on English Newsportals for example The Local in Sweden.
Information on housing for rent can as well be found from public or private housing agencies, listed in the phone directory as bostadsforetag. However, an effective way of finding somewhere to live always is by asking personal contacts if they know of anyone who will be vacating their accommodation, and contacting their landlord directly.