What do I need to prepare for traveling back to Thailand with my Thai wife?

WWW.thaievisa.go.th

Flying would probably be best. When you arrive you will likely need a visa also.. I would recommend packing a bag, tooth brush clean underwear stuff like that. You can buy those here if needed.

look at Thai embassy in your home country

Why you want to go back to Thailand now

Too difficult to go back to Thailand very expensive you have to spend a lot of money

Wait for next year

One thing to keep in mind... if you do NOT have a direct flight, you run the risk of having to be quarantined in a “transfer” country if anyone on your first flight is suspected of having covid, or is tested positive for covid. This quarantine will NOT exempt you from the mandatory quarantine once you arrive in BKK.

In order to get your visa, you will need a copy of your marriage documents, and a copy of your wife's Thai ID card. That will get you a 90 day type O visa based on marriage for entry. You will need flights, and quarantine hotel booking and paid for. You will need covid-19 insurance that covers at least US$100k. Your wife can go into government quarantine for free, but you can't. She can also pay for hotel quarantine to be with you. You will need to meet all the Thai Consulate requirements to get your Certificate of entry, and you will need clearance from the Australian government to leave the country. The consulate will fill you in on what they need.

I am in Brisbane but had to go through Canberra embassy for O-A visa

For a start you need to look at the requirements on the website for the embassy closest to you then ask questions.

Search group for insurance