A good Naruto yaoi oc fanfiction usually has well - developed characters. The original character should have a distinct personality, backstory, and motives. For example, they might have a unique ninja skill or a special family background.
The plot is also crucial. It should blend well with the Naruto universe. It could involve the oc getting involved in the main story arcs, like the Chunin Exams or the Akatsuki's plans. Also, the yaoi relationship should be developed in a believable way, not just forced. The characters should have chemistry and their interactions should be interesting. For instance, they could start as rivals and gradually develop feelings for each other.
Good Naruto yaoi oc fanfiction often pays attention to details. This includes getting the Naruto world's lore right, such as the different jutsu, clans, and the way the Hidden Villages operate. It also should have good pacing. If the relationship between the characters develops too quickly or too slowly, it can ruin the reading experience. And the writing style should be engaging, making the reader want to keep turning the pages to find out what happens next.