Christopher Athineos, who with his parents owns 150 apartments in 9 buildings, a mix of rent-regulated and market-rate units in Bay Ridge, Park Slope and Brooklyn Heights, said that while “obviously this is our business, you get close to it” — especially if you get to know your tenants well.

His parents bought their first property in 1968 and still live in one of their buildings. Mr. Athineos grew up with some of his current tenants and goes to their children’s baptisms and other events. He even agreed to help the niece of an older tenant scatter the ashes of that tenant when she passed away.

“I do cut people a break. I have a couple of senior citizens in Bay Ridge — one woman, her husband passed away a long time ago, she’s in her 80s, on fixed income. I’m like, ‘Sign the lease renewal, no increase,’” Mr. Athineos said. “Or I increase her $5, so she doesn’t feel like a charity case.”

For other tenants, he said he usually raises rent by 1 to 3 percent on the second renewal. “No one likes an increase on their first year,” Mr. Athineos said. “But I’ve made the mistake in the past where I don’t increase them for four years, then all of a sudden, you have to ask them for $75 or $100, and they’re like, “‘Oh my god, you’re killing me.’”

The key thing, landlords agree, is to hang onto good tenants — the ones who pay on time, take care of the apartment and call you when the radiator’s leaking all over the floor, but not, as one landlord said, “because the refrigerator makes too much noise.”

Minimizing turnover is important, because empty apartments have to get cleaned, repainted and repaired. And there is often at least a one-month gap between tenants, with no rent coming in. Some landlords avoid raising the rent at all when they have a good tenant, preferring to catch up to the market the next time they list the apartment.