Startup Small Business

Where personal funds are used to pay business expenses, the owner has either made a loan to the business or has contributed capital to the business. Ask him which.

If personal expenses are paid from business funds (which should not be done), it is a draw/distribution.

I'm not sure if you're asking about one or both. 

"What is the ideal way to deal with a LLC startup were personal funds are used to pay business expenses?"

The business expenses don't get treated any differently, just because personal funds were put into the business so that the expenses could be paid.

"Should the personal expenses labeled as owner's investment, or should be labeled some type of other expense?"

You don't track personal expenses for business recordkeeping at all. You would track Draws; the owner took funds to be used personally and it does not matter why or on what.

The best way is to start out asking if the LLC has elected to be taxed as a sole proprietorship, a partnership, a C Corporation or an S corporation.  That's usually when you find out they are clueless and made absolutely the wrong choice, mostly out of ignorance.