Forming an LLC, having an Operating Agreement (since your LLC may not always have only a single member), and hiring a good lawyer and good CPA to make sure your LLC follows the legal and accounting rules are the way to start.
What you want to do is avoid letting any claimant "pierce" your corporate "veil" to get at your personal assets. Basically, you need to respect the distinct existence of the LLC, and keep all your personal business, contracts, emails and other correspondence, bank accounts, tax returns, etc. etc. separate from those if your LLC. If someone sues you and claims that your LLC is your "alter ego," they'd demand inspection of all your and your LLC's accounting and legal records, to see if you've adhered to the formalities. When possible you want to avoid personally guaranteeing any of the LLC's debts.
There are other things you can do to protect yourself, such as getting business insurance, using well-drafted contracts for your clientele, vendors, etc., including proper disclaimers on your website, etc. etc.
See the guides linked below.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.
I agree with my colleague. It appears that you already have been operating as a business, so you should retain a lawyer and an accountant right away.
As regards protection against personal liability, please see the first link below (discusses corporations, but considerations are similar for LLCs).
As regards using an online service to help you form your LLC, my opinion is stated at the second link below.
Disclaimer: This post does not constitute legal advice and does not establish an attorney-client relationship.