Some folk might think getting a new visa every two years with all the criminal checks and mandatory insurance is a hassle. Only benefit is not having to park funds in a Thai account.
First check the requirements on the Thai embassy website in your home country. You then need to create an account and apply for the visa using that. You'll need to upload various documents. You don't have to complete the application straight away, you can save and complete later (normally within two weeks). There is an excellent User Guide that walks you through the entire process. They may request additional documents so just upload as required. You can follow the progress of your application via your account. The visa will be emailed to you as a pdf file that you print. You have three months to enter Thailand from the date the visa was issued. Foreign marriage certificates generally need to be certified by your embassy here then translated and legalized by Consular Services. Check before you arrive if there is anything you need to do regarding your marriage certificate in your home country, it can vary from country to country. When you arrive the priority is opening a bank account, depositing the required funds (unless your embassy provides income affidavits). Go to your local immigration office and get the handout of required documents to apply for your extension of stay, get everything together and after your money has seasoned for two months go and apply. It can be a bit of an adventure first time but if you're organized and patient you can navigate it yourself. Otherwise pay an agent some ridiculous amount to assist you. Good luck!
You go to immigration and get the latest list of required documents. Get them together and go apply. Don't rely on a note to yourself that's a year old as things may have changed.