Believe nothing you hear and half of what you see. Say that over and over again, especially if you have plans to visit a sales centre.
Do your own research but work with a local condo specialist who has negotiated numerous deals over an extended period of time (they will know all the good, bad and ugly buildings). Get a condo lawyer too (not your uncle in Peterborough). Condo contracts are ever changing and slippery.
Have a plan and work that plan. Running around willy-nilly simply exposes you to increased "risk". Develop a strategy and abide by it.
The number of units developers advertise as "available" is often very different from the number they have for sale. Unsold suites will typically have a uniform window treatment enabling you to get an idea how many units are actually unsold (versus how many the developer is putting on the market). The doorman or security guard is also a good source of information. Casually ask them how many units are 'sitting empty' and you may have a figure you can bring to the bargaining table.
Noise issues are a common problem and what some people consider quiet is another person's equivalent of a RUSH concert. Schedule viewings during the busy time of day and when viewing the suite with your agent, ask for a moment of silence and listen. Hard. Can you hear the neighbou's putting their garbage down the chute? It's also a good idea to open the balcony door. Even on the 50th floor, traffic noise can be extremely loud depending on wind direction.
Visit the building for the morning rush and afternoon return from work. Grab a coffee and a comfortable seat and see who your neighbours will be if you decide on this condo.
Don't be afraid to chat up people in the elevator (this is an exception to tip 1). Most are likely renters and happy to give you the skinny on noise and parking problems. Wait times for elevators can be a big issue. Ask people how often elevators are shut down for repair. The loss of a single elevator can add 15-20 minutes to your 'commute' to work - like being caught in traffic on the expressway.
If there is anything shady going down in the building, this is a good place to find evidence. It's also where you might get a chance to see any cracks in the walls. Remember, you are buying a piece of the entire building.
Ask your agent if you may take your own pictures of the condo. There are some privacy issues that may need to be respected but vacant suites are usually ok. Photos on real estate website are often taken using a wide-angle lens which can distort the 'size' of the space. You may also want to bring a tape measure along to see if that couch you bought will squeeze in (condo's are often staged with small furniture). Remember, square footage is measured from the inside of the walls, not the outside.
Ignore the Media (with the exception of simplycondos.com) Many of the publications out there, including the real estate section of major newspapers, is advertising masquerading as journalism. Which takes us back to tip #1.