Sure I'm not going to tell you anything new here, Tomo, but if you're going to day trade them then:
1. Don't pick shares that get a lot of their movement from opening gaps. Shares like HSBC are heavily influenced by what's happening overnight (they derive most of their earnings outside U.K.) as are oil shares that reflect what's been happening to the oil price overnight. Things like that.
2. Do pick shares that move smoothly in the style of your trading. E.g.: if you trade breakouts don't pick those that have a high incidence of failed breakouts. Trouble is they don't display the same characteristics forever and a day. Emg (man group) were marvellous for me some years ago (both going up and going down) with smooth retracement sand reliable retracement finishes. Then they started to go haywire with price darting about all over the place.
3. Have a flexible stable of shares and bring them in and turf them out fairly regularly.