Frankfurt Hauptbahnhof (HBF) is a big station. Not big like Shinjuku in Tokyo, but pretty darned…read morebig! One thing I always remember is to arrive to and depart from the station from the main entrance as there are several other entrances dotted around there. This is the best way to get my bearings as well as hit the DB First Class Lounge before boarding my train.
While it initially looks like it could be mayhem trying to get to your train track, there is plenty of signage showing arriving & departing trains. There are also plenty of cafes and restaurants to kick back in while you wait. I recommend finding your train track first, then finding a cafe or restaurant in the vicinity of your track so you don't get lost or caught in foot traffic.
When taking the train into Frankfurt HBF, just remember to look for a giant windowed archway with an equally giant hallway toward the center of the building, and that will lead you straight to the main entrance.