on the ES, if it opens inside yesterdays range and volume is less then about 150k contracts total in the first 35-45 min. of RTH, then it usually means big players are not around (yet) and ES will probably get pushed around by the locals on the floor of the big S&P.....but that can/will change in an instant as soon as size moves in.
i look at other things as well, but none that i can share here.