A few things I've learned about rental real estate. If you buy an existing rental property, make sure you see the current owners "books". If they won't show you, run away. If you are not the handy type, make sure you have a network of people you trust to do repairs for you, before you buy. Talk to existing tenants, find out about any "deferred" maintenance items they've been complaining about. If you don't have the resources in the bank to cover vacancies and unexpected major repairs, don't buy until you do. Don't depend on credit cards and loans for your cash reserves. It's ok to use a real estate agent to find a tenant, but I have found that property managers don't care about the place like I do. Good luck.
"The four most dangerous words in investing are 'This time it's different.'" - Sir John Templeton