I look for support and resistance areas. If the extreme take us above important resistance, I look to see if that breaks or holds. Right now, ER and NQ stopped going up at yesterday's high. So, I would be inclined to short, with yesterday's high as my stop, and then will reverse if they continue up.
I have observed in the past that these opening HFEs either work really well, or they fail spectacularly - very good for SAR (stop out and reverse the trade.)