For beginners, 'The First Meeting' is a good one. It's a short and sweet fanfic that focuses on the initial encounter between Harry and Daphne. It gives a good sense of their personalities right from the start without getting too complicated.
A great beginner - friendly Harry Daphne fanfic is 'Daphne's Discovery'. It's about Daphne finding out some unique things about Harry. The writing style is very accessible and it's not overly long. It gives a nice introduction to the relationship between Harry and Daphne in the context of the Hogwarts setting.
I'd recommend 'Harry and Daphne's Hogwarts Days'. It's easy to follow and has a simple yet engaging story. It shows how they interact in the school environment, deal with classes and also start to form a connection. It doesn't have a lot of complex plotlines that might be confusing for new readers.