You are a new seller. You are going to attract more scammers than legitimate buyers.
You can avoid non-paying buyers and cut down on scammers trying to make you think they paid when they didn't by not using auctions, and requiring Immediate Payment for Buy It Now's (on the listing form, at least the more advanced one), and requiring the buyer to provide payment info and authorization to make a Best Offer in your Buyer Requirements page. Note that this makes combined shipping discounts more difficult.
Note that anyone requesting you to contact them outside the eBay message system (email or text or phone) is almost certainly a scammer trying to get your contact information (e.g. to send you a fake payment message). Any mention of a gift card is also a red flag (they make the real money getting sellers to buy gift cards to send with the package for which they "pay" extra in the fake payment message).
Respond to any message wanting you to text or email or call that you only communicate via eBay messaging, and cancel for non-payment after the 4 days is up if s/he has already committed to buy. Make sure your Buyer Requirements are set up to block anyone with 2 or more unpaid cancellations in the past 12 months and those with primary shipping addresses in locations you don't ship to (and opt in or out of the pre-authorization experiment as your situation warrants). Add anyone who doesn't pay to your Blocked Bidder/Buyer List (and anyone wanting you to contact him/her outside the messaging system). But the scammers can create new accounts a lot faster than eBay can remove the ones that prove to be scammers. And some have the skills to hijack established accounts to scam with, so don't think it's only new accounts that can get you. Be wary of anyone requesting anything out of the normal flow of eBay business (you list, possibly they ask legitimate questions solely with the messaging system, someone uses the buttons you choose to buy/win the item, they pay, you ship to the address given with the payment, eBay tells you on the website--don't rely on email or text messages and don't click any links in them--that the funds have cleared and it's OK to ship).
