How do I enter expenses that were paid out of my personal checking account?

You are the vendor; do you want to get reimbursed for these expenses?  If yes, enter bill under your name as Vendor and cut a check to reimburse yourself.  When you enter the bill, code it to the specific job it is related to.  If you don't want to get reimbursed, code to Owner's Equity.  But, I'm not sure how your company is set up (sole proprietor?  LLC?), so might be a question for your accountant.  Hope this helps!

I use a "cash" bank account to record out of pocket transactions. I enter the expense like any other, except I then add a line with a negative number equal to the expense, coded to the "owner's contributions" equity account. This results in a net zero check, properly records the expense, shows that it was paid for by non-company funds. Keeping the cash account balance at zero shows at a glance that I have properly recorded the offset for each transaction.

Your name is not a Vendor name. You do not enter a bill for your own expenses.

If this is a sole proprietorship, then your name is on the Other Names list.

You can write yourself a reimbursement check for most things.

You can enter this into Owner Contribution (an Equity account) if you don't intend to repay yourself.

You need to learn the rules for your entity type for business expense tracking. Your fuel for your personal car likely is not a business expense. You might be able to be reimbursed for mileage, or maybe not. It depends on the tax rules.

Anything you enter into QB can be Job Tracked, and remove the checkmark so it is not billable.

Anything you do for a job really should be entered using Items, for good Job reporting.