Self-Employed Taxes (Canada) tl;dr
CPP is payed at the end of the year. Save 6% of your gross income for this.
Payed at the end of the year. These are bracketed by income, but to make calculations simple I just keep a flat 29% of my monthly income.
If you are operating as a freelancer or small business and are expecting to make over \$30_000, register for an HST account here and charge the customer directly on top of net fee (13% in Ontario).