In a great 11th Doctor and Amy kiss fanfiction, the setting plays an important role. It could be set in a familiar Doctor Who location like the TARDIS or an alien planet. This adds to the authenticity and the 'Doctor Who' feel of the story. Also, the emotions described during the kiss are key. It's not just about the physical act but the feelings that lead up to it and follow it, like love, confusion, or a sense of new beginnings.
A good fanfiction about their kiss would also likely have an interesting plot. Maybe it's a story where they are facing a great danger and the kiss is a moment of connection in the midst of chaos. Or it could be a story that explores an alternate timeline where their relationship develops differently. The writing style should be engaging, with good dialogue that sounds like the characters we know from the show, and descriptions that draw the reader into the world of the story.
A good fanfiction in this case would have well - developed characters. It should capture the essence of the 11th Doctor and Amy as we know them from the show. For example, the Doctor's quirky and somewhat alien nature, and Amy's strong - willed personality. The build - up to the kiss is crucial too. It shouldn't feel rushed but rather a natural progression of their relationship within the story.