Want to run a contest for my small business, any laws or guidelines I should follow?

I am looking at setting up a contest for my small business to help generate new clients and get my name out. I was planning on going to my local wellness center and purchasing a few items then combining them with a gift certificate for my consultation services (I offer holistic health consultations). Would there be any laws or guidelines for Nova Scotia/Canada I should be paying attention to before I do this? I am still new to owning and operating my own business, trying to learn the ropes!