Little things can mean so much

Cadance's foreleg looks worryingly dislocated here

Do you recognise the screenshot above? I'm sure you do: it's from the little montage near the end of "A Canterlot Wedding", in which the real Cadance joyously oversees preparations for her marriage to Shining Armor. This particular scene lasts about three seconds. The reason I'm posting it here, though, is to illustrate something I think can really help with making your fanfic work: picking up on little details.

In my fic We Who with Songs Beguile, I write from the perspective of a rather crotchety old blue jay named Mazarine. He's the guy you can see perching on Cadance's tail in the picture. Late on in the story, he talks about his continuing grudge about what happened at the song rehearsal you see above. (The story itself is set rather later, in the latter part of S3.) Here are some extracts from his rather long-winded moan about it:

I was ... with five of the others – including Roseate ...  [Cadance] was right there, and for some bizarre reason we were made to perch all over her ... [Fluttershy] really wasn’t messing about: the big stick. Teeth bared. Eyes closed. Wings flared ... I was actually allowed to perch on the alicorn’s tail

All of that – every last bit – fits in with what you see in the picture above. Mazarine is there: check. There are five other birds: check. Roseate is also present: check. (He's the reddish bird above Cadance's ear.) Perching all over the alicorn: check. Fluttershy: check. Big stick, bared teeth, closed eyes, flared wings: all check. Mazarine perching on Cadance's tail: check. I actually watched this scene about six times while I was writing the story, to make sure I hadn't messed it up.

Now, you may think that's a lot of effort to go to for a three-second scene. But I disagree: it's those little things that make a story believable within the confines of the FiM universe. Take another example: if you have Applejack call Rainbow "Dashie", at least outside a certain sort of shipfic or just to wind Rainbow up, you've lost me. Because she doesn't. Only Pinkie Pie ("Over a Barrel" and "Too Many Pinkie Pies") and Fluttershy ("Keep Calm and Flutter On") have ever used that particular nickname in canon.

I'm sure that someone who read through all my ponyfics could find places where I'd made similar mistakes. I'm usually quite good at Mane Six characterisation and dialogue, but I'm certainly not infallible. Even so, I think what I've said here remains valid: that attention to this sort of detail really does pay off.