I decided to rent my old place recently, a few things to look at. The rental income does not count for your debt to income ratio with the bank for your loan on the new house. Most banks want two years of consecutive rent for this to count as income.
My experience is don't go into it expecting to get much more than your equity paid for, I lived in the house for 5 years no issues except the ac being replaced when I first moved in, but that was a known issue. As soon as I rented it the water pump on the washer shot crap, after that the mother board on the heater went out, didn't know it had a mother board, after that a switch in the heater went out. Nice thing about the repairs is that it offset the taxes...
The renter wasn't horrible, but not the brightest after the second month of rent being late she told us rent came from her child support check, which comes the second Monday of the month. Fine by me I just need to show income. Which brings up the biggest point, don't do it unless you can make all the payments without the tenant depending on city or county it can take awhile for an eviction, and you still have that mortgage. We just saved for six months as if the tenant hadn't paid before starting to rent to see how it influenced our finances. We then put that into the crap tenant account in case they didn't pay for six months.
After a few months we saw the tenant had a dog crate ISO on Facebook, but we had not said she could have a dog, so that was fun to get the dog smell out. Then after a few months she said the caulk around the tub had started to peel up, she would fix it if I gave her the supplies, not sure what happened to the supplies but I just dropped $500 putting in a new tub surround because the old one was never caulked.
Even after that I'm still glad I have it, it's giving me the equity to buy something else and someone is paying for it for me. You have to have the right mind set and treat it like a business, not like your friends living there.