@Tara Montgomery
If you're selling, it's about the payer.
If you're selling a single-family home to an owner-occupant (I don't know if you are) – the "perfect" seller-financed note is 20% down, 10% interest, 10-year term. But that's a unicorn.
Why? There's a balance between what's good for the seller and what works for the buyer.
If the buyer can't afford the payments, they've been set up to fail. No one wants that.
In today's environment, try to set the interest floor at 7%... more of you can make it work. Avoid a 30-year term unless the payments aren't affordable otherwise. 15 - 20 years if you can. Minimum 10% down. I'm not a fan of balloons... but if there is one, I suggest 7 years or longer.
You can look at area comparable rents. Keeping your payment in the range of rents (allowing for expenses a homeowner will pay and a tenant doesn't) tends to keep owner-occupants on track.
Your attorney or an attorney-owned title company can create the docs and manage the closing. There's something called a "lender's title policy" you should ask them about and have your buyer pay for at closing.
After you close - use a loan servicer to collect payments. Your promissory note can require escrowing taxes and insurance. A loan servicer can collect this and make tax and insurance payments. Other benefits here also.
Finally... the best advice I can offer is to use a third-party underwriter. They'll take a loan app, pull credit, verify income, and verify the ability to repay. Your buyer can pay for it at closing.