If you’re on the subway, take the 7 train to Hudson Yards/34th Street. If you want to beat the crowds out of that station, stand in the front two cars of the train. If you need an elevator, then you’ll have to walk along the mezzanine to the far downtown side of the station. Otherwise, I recommend using the bank of escalators.
Once you’re outside:
If you’re attending as a fan, walk towards 39th street, where you’ll be tapped in by ReedPOP staff.
You’ll be guided downstairs, to Hall 1C. There, you’ll go left to get in line for a panel (and eventually, a wristband), or you’ll go to the right to get in line for entry to the show floor upstairs. The info desk will have a giant display board listing which panels are available.
If you’re a VIP badge holder, or one of the other non-fan groups, then you’ll line up outside the entrances to 3-C and 3-E upstairs.