Meet with the story team. Before any other part of the writing job can be finished, you have to meet with producers, other writers and various story team members to settle on the overall story arch for the season, as well as determining how each episode will lead into the next.
Writing an ending for your episode that will lead seamlessly into further shows, as well as writing a smooth transition into yours from the previous ones, are very important parts of a reality writer's job.
Prepare a script. The beginning of a reality writer's job usually begins once all the footage is shot. You need to start by watching tapes and reading over field notes. This will keep you updated on the action that happened and allow you to start planning out your narrative.
Check in with editors. In typical reality TV post-production, teams of editors work to cut hours of footage down into episodes.
Usually, many different teams can work on a single episode, which means they usually don't know what the other teams are working on. It will be your job, therefore, to liaise with each team of editors about changes to the components and story arcs taking place in the show.
By briefing editors on how the show is going, you can make sure a coherent story comes out of the final edit.
Meet with executives. Once an episode is edited together, the writing and editing teams attend a screening with the executive producer. After the screening, you'll get notes on what the executive likes, dislikes, wants more of, or wants cut entirely. You might then be required to conduct extra pickup interviews with the cast to expound on the story arc, or create an entirely new arc altogether.
Ultimately, the executive producer has the final say in what goes on air. You may have to write and rewrite your script, or even shoot more footage to accommodate an interesting twist that emerged in post production.