There is no hard and fast rule for picking the stocks. But the thumb rule that i follow are that they should be liquid and should be in F&O. And they should be priced above Rs.1000.
(Because then even a 2% move which is not very irregular can give Rs.2000 intraday in 100shares). And most importantly once you have chosen 2 or max 3 of these stocks then stick to trading them only, every day.