I live in an owner-occupied triplex. Definitely keep plenty of money liquid. Within months of buying our place, our tenants' toilet stopped flushing, and we had to replace the entire main sewer line for about $8000, plus spent $800 on sod to replace what was dug up. About a year after we bought the place, we had to replace the AC/heat blower and all the duct work to the tune of about $5000. And over the first couple of years, we ended up replacing all of the old appliances in the house, so we've purchased 3 refrigerators (actually, I think we got one free from a family member), 3 washing machines, and 3 driers. We DIY lots of small stuff, but these were all beyond our abilities. Even with an inspection, you never know what's been deferred or shoddily done (for example, the old pipe was terracotta from the 30s).
Our triplex makes financial sense to us because the rent from the other 2 units covers routine expenses--interest on the mortgage, insurance, property taxes, routine maintenance, and supplies for landscaping/gardening. The cash we take from our salaries (which is less than market value for our unit) pays the principal on our loan, major (voluntary/cosmetic) renovations, and the couple of major repairs mentioned above. For tax purposes, the rent we take in is more or less offset by tax-deductible costs of owning the property. I'd look for numbers like that, where what you'd be paying in rent goes toward purchasing the property, while someone else pays for most of the costs of carrying it. We also are in an area where we think the property value will increase over time, which helps, but as long as it doesn't go down much, we're way ahead of where we would be if we'd been paying rent.