Not all incorporations are made equal. For LLCs, I feel it depends on the state of incorporation as well as the number of members. I could be wrong, but an LLC that is either incorporated in states like CA or only has one member, can have its corporate veil easily pierced.
Another thing I've heard recommended / try to do is to always sign as a member of a LLC (include your company position next to your signature) so it's clear you're signing on behalf of the LLC and not personally.
IANAL: I feel this depends on whether or not the LLC has two or more members. When an LLC has one member who is active, it's not much better than a sole proprietorship. Having great legal protection is a myth about single member LLCs that needs to be broken. It's relatively easy to pierce an LLC's corporate veil. Then again someone may prove me wrong. You need to talk to a lawyer.
If you don't want to read the book, talk to a lawyer. Expensive lawyers have the first hour often (usually) free. My less expensive lawyer offered "one-hour consultation plus all filing fees" for $500 deal. That would be money well spent.
imo if you want more protection, you need a C-Corp or a more than one member LLC... there are caveats to both routes and everyone should talk to a real lawyer about this or books from say NOLO