Run or Pass?

[stripes1977]

As a new Umpire (I now have 1 scrimmage under my belt at this position), I've found that sometimes its difficult to read the play. I'm trying to key on the OL players, but there were a few instances where I read run, and then I see the ball flying over my head and I'm already moving laterally and not in a good position to move up to the line. Maybe I'm trying to watch too many people.

I love being in the field as opposed to the sidelines, but I guess my unfamiliarity with the position has me scratching my head as to how in the world one can actually see things like holding and illegal blocks?

So I guess my questions are: Does anyone have any particular player or keys that they use to read run/pass?....and Are there any rules of thumb to maybe help eliminate some of the mass confusion going on between the tackles to help actually SEE some things?