How Do You Make Someone Comfortable with Rimming?

So I’ve been wanting to get into rimming with my partner, but they’re a little hesitant about it. I get it—it’s not something everyone jumps into right away. I made sure we talked about hygiene and comfort first, and one thing that really helped was showering together before. It made everything feel a lot more natural and clean, which put them at ease. Now they’re starting to enjoy it, but I don’t want to rush anything. Any advice on making them feel even more comfortable?