Pay attention to the annual filing fees in your state for LLCs. That makes it prohibitive in some states for small side-project type endeavors. (MA filing fees are $500 registration and $500/yr for the annual report filing.)
And if you end up close to the end of the year before filing, hold off until January to form the LLC if you can. Otherwise they’ll expect the annual fees ($800 in California!) for the partial year. And if you end up paying late, they’ll come for the penalty as well.
