Stitching - All Hermes bags are handmade and stitched so all stitches should be flawless. Any signs of inconsistencies, irregular patterns or crooked seams then the there is a chance of it being fake.
Handles/Bag shape - With brand new bags, when standing, the bag should show no signs of slouching or bulging. It should stand properly as should the handles, straight up or down.
Logo - The logo for Hermes bags are always neat, elegant and in a specific font. On many fakes you will see fonts and writing that is irregular and blocky/out of proportion.