There is a rule of thumb for visiting which is that you shouldn't visit for longer than you are living somewhere else so max 182 days a year or so. However, immigration can always let you in or turn you away based on their gut feeling of your intentions. They can let you in with a default visa of up to 6 months, they can let you in with a shorter visa of something else or they can turn you away completely.
When you enter Canada, you should preferably have some proof of employment so that you can show Canada immigration that you will be going back. If they turn you away and tell you not to come back unless you have documents x and y, proof of employment, rental contract, whatever, it would not be wise to try to enter somewhere else because they will have documented this in their computers. If you get on their nerves too much, they can actually ban you from Canada for some time. If you are flying, you should of course have a return ticket.
As I recall, you are from the US, so you should look into if you can get a Nexus card. If you can, your border crossings will be more automatic and less talking to immigration officers so it might be easier for you to visit.
