Criteria metrics for finding market to flip

Hi BP

I'm interested in what sites are recommended to become familiar with help in researching a market area. My strategy, fyi, is to flip properties initially, and then migrate to rentals down the line.

Some metrics I've seen are: (1) days on market, (2) house price range including property taxes, (3) local proximity, and (4) # of properties sold within last 3 months.

Again, any other websites or metrics I should consider? Thanks in advance.