* Don't store expensive alcohol or munchie relieving foods in common spaces.
* Some people don't close the washroom door when taking a leak, even with strangers around the house.
* Establish a dish washing and house cleaning protocol. Split the costs of all supplies, or have a piggy bank for this stuff. Can be used to order pizza too.
* Some people believe Febreeze helps clean your fart repository sofa. Or mask the odour coming out of the organic waste bin on a hot day.
* A low rent is more likely to attract a problematic tenant. I've seen tenants ranging from complete slobs to the two students who could not pay the rent and eventually set the basement on fire (by accident). Fix up the place at least cosmetically, buy low-maintenance plants, take pictures on a sunny day with plenty of natural light, and up the rent. Good tenants are worth the extra work.
* A short-term tenant is more likely to treat the place like shit.
* A laundry machine in the house is great. If not available, check that the laundromat is within walking distance of someone carrying massive laundry bags, and that it closes at 12am and opens at 6am, or is open 24/7.
* A walking-distance grocery store and/or fruit market is a massive plus.