Score/Reviews
Actor/Actress
Plot
Generally I make sure to check to see if a drama has a high score or not. As more often than not, a high score will mean that it's a decent drama for one reason or another. Of course some times you get fanboys and fangirls who give the drama a 10 just because their favorite person is in there. Then I go to the next criteria and decide whether I know people in it and whether I like them or not. Lastly if everything fits the first two, I'll watch it if I like the plot.