How can I make the best of a nanny job if I'm paid $30 CAD/day by the Mom of the 7 year old girl I'm considering taking care of more while she's at work?

I want to be able to afford a phone in case of emergencies, but I also want enough left over to do things with her like bring her to museums, etc.

If location is needed to give a more helpful answer, I live in Ottawa, Ontario, Canada.

Thanks in advance!