Link a bank account, provide your SSN, confirm your billing address by linking a debit or credit card.
Have access to bank statement, credit card statement, photo ID, keep PO/Invoices from suppliers, tracking numbers if selling physical goods in case PayPal asks for them.
Start low value and slowly, gradually grow to higher value or volume. No sudden peaks, no get rick quick schemes, flood of money overnight. Have capital on hand to keep business running because being a new to accepting payments, your payments will be subject to PayPal's 21-day hold (there are tasks you can do to release the funds sooner such as ship your orders and providing tracking numbers or marking transactions as processed to shorten the wait to 7 days, you can ask the buyer to confirm receipt to release funds). Basically do not bite off more you can chew. Play the long game.
Try not to lean on seller protection too much and self-insure (put aside a % of each sale to cover the occasional disputes and chargebacks) and by resolving problems with the buyers because they do happen, as quickly as possible and focus on the next sale.