Utilities, pipelines, and big staple (food) producers. Energy stocks also. There are a lot of LLP's which are partnerships that are traded also, e.g. Acme Pipeline Partners, Ace Fertilizer Partners.
Make sure they are profitable, and the dividend is smaller than the profit. Quick test to make sure they are healthy. I just use finance.yahoo.com to check on their profits and such. After that, if you have a 401K or IRA, a lot of times the company running it has a stock research function for free. So after you ID a few candidates, do a deeper dive with the free research reports you get.
Then you have to be patient. You'll get one or two opportunities to buy each year. You build up cash, and then when the market tanks, you buy the boring stocks and lock down a fat dividend check. Rinse and repeat.
Consider this. If you had done this during the last sell off, you could have spent $200,000, and end up with a $28,000 dividend check each year, likely for life. And that will grow with inflation.
The reason this works is because as a small investor, you are nimble. If you have your money parked in cash making 0.2% interest for 9 months, no one is screaming at you. And when the market crashes, you don't have to bail to protect your $100 Billion fund, instead you can buy.
Also, DON'T select automatic dividend reinvestment. You want the dividends to build up as cash so you can go shopping the next time stocks are on sale.