Both the easiest to start and lowest in taxes and fees is the sole proprietorship, but this isn't incorporating. You're just declaring yourself as a business and accepting all the risk (though PL and GL insurance helps). When dealing with businesses, this is frequently referred to as a 1099 contractor as opposed to a corp-to-corp.
Next best option for an individual is the LLC since everything can be passed through to yourself to avoid any double taxation. There is more overhead to set it up, but it also comes with some protections (hence "limited liability" in the name).
Of course the standard disclosures apply, check with your local CPA, lawyer, tax advisor, etc.