To be honest, not too much you can do when you're on the waitlist. It's called what it's called because you're supposed to be... waiting.
But, there are things that could help you improve your chances of converting. The best thing you could do is to improve your profile. For many, at this point it's too late, unless you get a last-minute promotion or do some crazy volunteering and you tell Rotman about it. The easiest thing most people can do is to improve their GMAT score if they're still sub-700, beyond that there's not much difference. The last thing you could do, which will be very difficult for many, is to attend all the Rotman admissions events. If you're not in Toronto, this will be very difficult. If you are in Toronto, you're lucky and the face time really helps make sure that you're at the top of their mind and they know you're still very interested, it could make a world of difference.
As for whether or not it's a good thing, that really depends on you. Probability of converting to waitlist is low, the waitlist is essentially a pool of candidates for "just in case someone with an offer backs out and we need someone last minute to fill the Class roster". So while you're not outright rejected (which is good), you're also waiting with a low hope of something happening and you can't move on (which is bad). It's up to you how to interpret the situation.
Respond with politeness and professionalism. Tell them you understand the situation you're in and that you're grateful you're still in the consideration. Ask them what you could do in the meantime, and what would help them consider you in better light. Do not keep pestering them with emails asking for an update. This reeks of desperation, and it gives them an easy reason to move you to the reject pile. Remember, one of the factors of admission is how hireable you are. Does someone who keeps bothering someone with emails seem like someone you might want to work with?
My personal suggestion on how to look at this - treat this as a rejection and move on. Check back every now and then to see if anything's changed, but if you're just hanging on and waiting for positive news, you're not moving forward and you may never get it. Work on other MBA programs to improve your pool of choices.
And that is the last thing you could do while you're on the waitlist to improve your chances - but it's a double-edged sword. Getting an offer of admission to a competing business school can give you a better chance of getting an offer from Rotman, but that's if your profile is at the border of being admitted - and you just never know. You could guess based on your own assessment of your profile, but nothing is for sure. Using an offer of admission from, say, Ivey could trigger Rotman to look at your application again, or if you were in the bottom half of the waitlist pool they'll just tell you to accept the other offer. It's a gamble.
Bottomline, my opinion, waitlist sucks, not much you can do except... wait.