One significant issue is Timing. That's why Advanced Costs are held as an asset, to be reimbursed by the client, which washes them away. You don't include them as COGS or any type of Expense under these conditions, and the reimbursement is not Income (not gross or net). Think about the lawsuit that drags on over 3 or more years.

Your State Bar Association should be able to provide you with good attorney accounting references, to help you understand how operations are handled, client prepayment (retainers) are handled, IOLTA funds are handled, and case costs are handled.

If this is new to you, get some mentoring, too.