Lots of good technical advice here, better than I can give (nor mostly even understand). But here's some real-world practical issues I've encountered.
Placing the router near an outside window was already mentioned. Can be good advice, if the window is plain glass. Here we just had new windows installed with UV sun protection, and they block signals, I presume due to some metallic content in the glass. I can even have trouble with my cell signal, and sometimes will open the window to improve reception, or sit outside on the patio.
Your house structure and insulation can be a factor. Homes once used reflective foil sheets in the walls for temperature insulating purposes. Does your house have aluminum siding?
Many newer condos and apartment buildings have metal framing and support beams, rather than wood. A router placed near an outside wall containing a metal beam may be partially blocked. And safety code requirements for fire walls between adjoining units may result in more metal in the walls, masking a router's output on that side of the dwelling.
Therefore, try to find a router location close to a "clean" (signal transparent) outside wall or window, possibly in a porch or breezeway, with minimal structure. Your router and any auxiliary antenna need a straight line-of-sight to whatever outside areas you want to cover.
Last, make sure you use full security code protection. If your WiFi is going outside anyone can access it. Poaching your signal will not only slow down your own usage, but may have legal and personal security consequences.
I don't know how it is in Canada, but in the US some people have faced entanglements when illegal online activities, like kiddie porn, were traced to them because the real perpetrators were stealing their WiFi. The other major risk is hacking of your computer and data theft.