Where to begin? Is being a landlord as bad as some say it is?

I have decided as an RN for 30 years and tired of punching a clock, to invest in real estate. I bought a brand new town home a year ago, but tired of big payments. Now decided to sell, and get serious into real estate. I thought buying rentals would be easier to start and maybe do some flipping later when I have some cash. I have heard horror stories about being a landlord. Is it really that hard? And any advice on how to start in this investing.