I've obtained a judgement against an individual for $1900 plus court costs in Texas small claims court. After 30 days elapses, I can file for a writ of garnishment or a writ of execution. If I want to go after their bank account, how do I find out where they bank? How do I find out what various accounts they have?

Getting the writ is the easy part.. but finding accounts to garnish is all on you. I'd recommend hiring a Private investigator and see what they can dig up. Its going to cost you some money... but they have far more contacts and resources than you have.

You can ask the court to require that they file a financial statement. Whether the court will do this, I am not sure. A PI can run a credit report that may include the info you need. So it may not cost too much.

Getting a judgment is the easy part, collecting is another story.

You can ask the court to require that they file a financial statement. Whether the court will do this, I am not sure. ...

Or, in some places a judgment creditor can require the judgment debtor to be examined under oath as to their financial affairs. In other words, the OP could ask the debtor questions under oath.

The problem is, of course, once the debtor is forced to disclose this information, there would normally be nothing to stop the debtor from emptying the account before garnishment levy upon the account could be accomplished. That's why it is often a better idea to somehow figure out what bank account the debtor has, and hit the bank with a levy without warning.