He could work at Weasleys' Wizard Wheezes. He has a good relationship with the Weasley family, and it would be a fun place for him to work, helping with inventing and selling all kinds of magical pranks and toys.
Hagrid could be a great help. He has a lot of connections in the wizarding world, especially with those related to magical creatures. He might introduce Harry to someone who needs help with taking care of or studying magical beasts, and thus get Harry a job in that area.
He could work at Flourish and Blotts. He's very knowledgeable about magic, so he could help customers find the right books. It would be a great job for him as he loves to read and study magic. He could also recommend books to young witches and wizards starting their magical education.
Perhaps Harry gets a job as a magical tutor for some young wizards. The story could develop as he tries to teach them the things he's learned over the years. He'd face challenges like dealing with difficult students or trying to teach advanced magic to those who are not ready. His experiences at Hogwarts would come in handy, but he'd also have to learn new teaching methods.
Well, he might work at Weasleys' Wizard Wheezes. He could help George and Ron with inventing new products and dealing with customers. It would be full of magical mishaps and lots of fun.
Well, he could work at Hogwarts during the summer for a change. Maybe he's helping Hagrid with the care of magical creatures. He would get to interact with new and dangerous beasts, and at the same time, he might learn some new spells to keep them in check from other professors.
Obviously Harry would be one of the main characters. And Hermione might also be involved, perhaps she helps Harry get the job or gives him advice on how to do it well.
Well, Harry could marry one of the veelas. Given their beauty and allure, it would add an interesting dynamic to the story. Their relationship could involve Harry having to deal with the jealousy of other wizards and also the cultural differences of the veelas. Or he could marry a descendant of one of the founders of Hogwarts. This would tie in a lot of Hogwarts history into their relationship, and their wedding could be a grand event that unites different factions within the wizarding community who have ties to the founders.
Maybe Dumbledore, if he were still alive in the fanfiction. Dumbledore was highly respected and had a great influence. Knighting Harry would be a way for him to publicly recognize Harry's achievements and heroism on a grand scale.