If a buyer defaults, your options fall into two general categories: Mutual Agreement Options: 1) contractual solutions; 2) negotiation; 3) mediation. Dispute Resolution Options: 4) arbitration; 5) small claims court, and 6) litigation in the superior courts.
The best way to protect yourself is to do what banks do, require a downpayment that will at least cover the costs of a forclosure which is around $3000, and do a credit check to see what the credit issues are before agreeing to such an arrangement.
How Does Seller Financing Work? A bank isn't involved in a seller-financed sale; the buyer and seller make the arrangements themselves. They draw up a promissory note setting out the interest rate, the schedule of payments from buyer to seller, and the consequences should the buyer default on those obligations.