[Crazy Flamer]

Well, I'm about to purchase a piece of real estate as an investment and I'm wondering if anyone has any tips to share. I'm looking at purchasing a condo in the inner city. This is my first time venturing into real estate investment and I'm hoping for some insight:

1) Any red/green flags to look for from potential renters?
2) How can I do a credit check on potential renters?
3)Any specifics I should include in the rental agreement? Is there a template I can use?

I've been coming across all these real estate investors in the US that seem to buy up copious amounts of property. I'm guessing the real estate investment game is different down there? In Canada, is they any way to grow a real estate portfolio besides constantly putting down 20% on each property?