Look for markets with a strong rental demand, low demand to own property, and good prospects for growth. Maybe start with your fav vacation spots
It's crucial to accurately estimate expenses: Mortgage, Taxes, Utilities, Insurance, Cleaning, Maintenance, Furniture, Linens, etc.
How much are other rentals getting. You should be able to make 3x the long-term rental rate. Check out Zillow or Rentometer for estimates.
Revenue = Average daily rate X Occupancy
Your next big decision is who's gonna run it. It depends on how much time you want to invest.