--Not legal advice--
Oklahoma's laws governing business entities, like many other states', are modeled after Delaware law.
In Oklahoma, we file Articles of Organization to form an LLC, and a Certificate of Incorporation to form a corporation. Both the Oklahoma General Corporation Act and the Oklahoma Limited Liability Company Act fall under Title 18 of the Oklahoma Statutes (which is titled "Corporations"). But the Oklahoma General Corporation Act applies only to corporations - not LLCs.
An LLC has many characteristics of a corporation, and some doctrines (such as piercing the "corporate" veil) may apply to both types of entities. But I would not call an LLC a "corporate" entity (again, Missouri law may be different).
I agree that LLC owners need to be careful to operate their LLCs as business entities separate from their personal business. But I disagree that anyone needs to hold "meetings" with himself to do it. I would do the following:
1. Execute and maintain an operating agreement (whether the LLC will be manager-managed or member-managed);
2. Follow the provisions of the operating agreement in managing the LLC.
3. Execute all contracts in the name of the LLC, in your capacity as manager or managing-member. If the LLC has a manager, then the member should execute a written consent authorizing any transaction requiring the member's consent, as set forth in the operating agreement;
4. Set up a separate bank account in the name of the LLC and transact all of the LLC's business (and none of your personal business) through the LLC's bank account.
5. Keep accounting records of the LLC separate from your personal accounting records.
6. Designate an authorized agent, pay any required franchise taxes, file annual certificates, etc. as may be required by your state.
I have never heard of a case where a court disregarded the LLC as an entity when the owner had done these things. If anybody knows of one, please let me know.
I think people run into trouble when they misunderstand the protection that an LLC provides. There are two protections that many people think LLCs provide, which in fact they do not provide:
First, the LLC is not going to provide liability protection from damages that result from your negligent behavior. So if you form an LLC to hold your rental properties, but you personally manage your rentals, the LLC will not shield you from personal liability if your property burns down because it did not have smoke detectors. Even if you hire a property manager, a judge might decide you were personally negligent in hiring an idiot as your property manager and allow a suit against you personally.
Second, the assets in an LLC that you personally own are not necessarily safe from a judgment against you. Courts, at least in some jurisdictions, have the power to require you to surrender ownership of your LLC over to a judgment creditor to satisfy a judgment against you.
So be careful to preserve your LLC's status as a separate entity, but also carry lots of liability insurance.