To write a good 'gaara x oc' fanfiction, you need to be consistent with the Naruto universe's lore. Include details about Suna and its culture. Let the relationship between Gaara and the OC be a journey. They can face challenges together, like threats to Suna or personal demons. And don't forget to add some emotional depth to their interactions.
When writing 'gaara x oc' fanfiction, focus on character development. Show how Gaara changes because of the OC and vice versa. You can also introduce unique plot elements. For instance, the OC could have a special ability that Gaara finds fascinating. Also, use descriptive language to bring their relationship to life, like how they look at each other or small gestures they make towards each other.
First, understand the character of Gaara. Know his backstory, his insecurities, and his growth throughout the Naruto series. Then, create an OC with a distinct personality. Make sure their relationship develops organically. For example, start with a chance encounter that leads to mutual respect and then deeper feelings.