@GraceAn--Hello & welcome to the OfferUp Community Forum!! I hope you have a great time interacting with other buyers and sellers, explore the different forums, & sharing your thoughts!!
When selling items it's important to have a well lit area selected, take pictures at different angles, provide a detailed description, indicate if your price is firm or negotiable, & answer any questions in a timely manner. If you're meeting up in person choose a location with a lot of people, be sure you & the buyer agree on the location & time, as well as amount (so the transaction can go as smoothly as possible).
Also, if you can, have someone with you when you meet people; especially when you don't know them. I hope these suggestions help you!!