[]first time buying a rolex, what should I know? Please help

Hello, it’s my first time purchasing a Rolex. I don’t know much about watches and I’m not rich so somewhat nervous. It’s a wedding gift for my husband. I don’t want to mess it up. I’m looking for an open heart model similar to this one?

https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcS32GP7V3kesqscnNT1-3gz93WajwhddqMBFg&s

Where can I go to purchase one with this design, used or new , without getting duped ? How do I verify its authenticity if used?

And what are things you wish you knew prior to purchasing a Rolex watch?

Thank you so much watch experts of Reddit!