I've done freelance work as an independent contractor for years, which works well-enough for sporadic freelance work. But as I get more gigs and an established portfolio, are there benefits to forming an LLC to serve as the agent being hired, rather than myself individually, even though there's only one of me? What other benefits/disadvantages of forming an LLC should I be considering as well?
LLCs were created for just this scenario: you're an individual or small business who wants to enjoy the protections being a company or corporate entity entails without becoming a full-blown corporation.
An LLC allows you to operate as an individual without putting your personal assets at risk. You pay taxes as an individual (in the US anyways) but enjoy protections against lawsuits and other risks operating a business brings.
Given that the costs of establishing an LLC can be trivial depending on the state you incorporate in, it's better to set up an LLC and protect yourself than to take on personal risk.
Besides liability limitation, which Paperjam covered well in his answer, LLCs also provides tax flexibility. You can elect to have your LLC taxed as a disregarded entity or as a corporation. As a disregarded entity, it's as if you there was no LLC. As a corporation, there is more paperwork; however, besides paying yourself ordinary wages, depending on your income sources, you may be able pay yourself dividends, which are not subject to self-employment tax.
It has always been a simple answer for me... start an LLC as soon as you make your first $125. I chose this because that is the minimum to start the LLC for paperwork in Ohio and to open a bank account.
That is my standard and I do it just to protect my personal assets. That is the core reason for an LLC.