You are confusing 2 different things. Business expenses and the standard deduction are completely separate and unrelated.
Personal deductions (mortgage interest, state and local taxes, gifts to charity and medical expenses) are deducted on Schedule A, and you can take the standard deduction if that is more than your itemized deductions.
There is no standard deduction for business expenses. Business expenses are subtracted from gross revenue on Schedule C to determine the net profit. You should always list ordinary and necessary business expenses that you can prove with reliable records, no matter how small they are.
