Hi there, @JessaNaeNae28!
I definitely recommend checking out our Tips blog which can be found here. I'd recommend that you don't send anything unless you're using OfferUp shipping. And it's generally a good idea to not exchange any funds until the item has been inspected because once funds are transferred the transaction is complete, so you def want to fully inspect items before handing over any cash.
Remember, you're in control of who you engage with. If you ever feel uncomfortable with a buyer or seller, you can always block them. We recently posted about Reputation over here, which has some helpful tips on trusting community members.