Have mixed income, how do I file? Half the year is w2, the other is self employed. Do I just calculate write offs from the self employed half?

You'll need TurboTax Self-employed to take your self-employed write-offs, which reduce your 1099 income. You can also enter your W-2. 

You should enter your 1099-misc, in full, and then enter your write-offs as well.

After you setup your self-employed work under Business Income & Expenses the software will walk you through all types of write-offs. Your business write-offs should only relate to your self-employed work.