Can i deduct a payment for busniess assistance

Hi, I run a mobile app for food recipes. It generates a small income and I will be paying taxes on it later. 

I want to pay my friend for 2 months. One day a week, to trial recipes. Just gig work.

I will only be paying this person about $350 dollars total. Do I have to have them fill out a W-9? And do they have to fill out tax forms?

Can I deduct this expense from my taxes, and if so how do I prove it. 

Thank you.