Hey! I was waitlisted last year and to improve my application I decided to do a fast-track SSW program at George Brown. It's only 8 months, and half of it is essentially placement which I thought would be useful as I think I was lacking hands on experience. In addition to that I did a little bit of volunteering. I think this year I also just strengthened my letter of intent and got one really strong rec letter that I was too scared to ask for last year (should have just done that) which made a difference.
There is a question in the app where they ask you what changed about your app since last year so i think it's helpful for them to see dedication/commitment, extra steps to improve ones app.
While you are waitlisted, I would recommend getting more experience in the next month or two, maybe another rec letter and potentially a better research methods grade if possible and send it in to strengthen you application and increase your chances of getting off the waitlist.