Where would I enter expenses incurred for a financial seminar I put on for potential clients? I paid thousands in lead generation, mailers, supplies, and meals.

That depends.

If you are an employee, the expenses would be deductible as employee business expenses.  Employee business expenses are no longer deductible on your Federal return, but you should enter them anyway, as they may be deductible on your State return.

If you are self-employed, you would deduct them as business expenses.