Please do
not use craigslist. There have been so many horror stories.
Try
www.kijiji.ca and always meet in a public place first (e.g. Tim Hortons, Starbucks). If you have to go see the house/apartment the person is renting out, make sure you go with a friend. Never go alone. Be sure to read the lease before signing so that you know your rights and responsibilities as a tenant. You can google, "Nova Scotia Residential Tenancy Act" for more information.
If you want a cheap option just for the first few days or weeks, you can search "YCMA on spring garden road - Halifax" or "International Hosteling on Barrington Street - Halifax".
I would avoid living in areas like Gottingen Street, Spryfield for safety reasons. You can find a nice place with affordable rent in the North end area(e.g. Quinpool Road, Robie Street, Oxford Street, etc); in the West End area (e.g. fairview, Clayton ParK, Bedford). These areas are on good bus routes and you can always call 902-490-4000 at anytime and ask the call centre agents which bus you need to take to go wherever.
There are a couple of agencies that help immigrants in addition to the one Singh listed like: ADAM, YMCA(has immigrant settlement programs, especially for families), Greater Halifax Partnership(can help with job leads).
Halifax is a beautiful city, lots to see(water, beaches, etc) and ofcourse, unpredictable weather at times (lol) but people are friendly. There is a Public Garden downtown, the Halifax Harbour, Immigration museum(at Pier 21), and many more historic sites. There is also a local farmers market every saturday starting at 7am(if you like fresh produce).
Welcome to Halifax and hope you enjoy your stay.