From not wearing a hat during an engagement with the queen to closing her own car door and dressing in a manner which was too 'Hollywood'.
But one of her biggest 'faux pas' came during an awards ceremony. When making a surprise appearance at the British Fashion Awards in December 2018, the Duchess of Sussex was photographed wearing dark nail polish - something the Queen has been known to consider 'vulgar'.
Commonly royals are seen to wear very light pink or nude shades of nail polish when attending events.
The Queen herself has sworn by the same colour varnish for over 30 years - a £7.99 bottle of Essie's Ballet Slippers.
And while she may have hit a few bumps in the road whilst learning to truly become a member of Britain's most famous family, it seems Meghan may have finally embraced her royal lifestyle.
This is because of a sweet gesture the new mum made in a photo on Instagram .
Posting on her and Harry's joint account, SussexRoyal, to mark Mother's Day in the US, the 37-year-old shared a snap of her cradling baby Archie's feet near some beautiful flowers.
While being quite arty, the photo also shows Meghan's nails, which are coated in a nude shade of nail varnish.
The simple, yet effective, nod to the Queen's beauty preference suggests the Duchess has learnt and taken on board the dos and don'ts of being married to a prince.