Eligible expenses for Self-Employed individuals must have been incurred for the purpose of earning income. Personal items such as clothing and toiletries are not eligible expenses, whether incurred for conventions, travel or other reasons. The only circumstances under which personal attire is deductible is when it relates to a uniform or special clothing.
Eligible Convention expenses can be entered as "Other Expenses" at the end of the expense section in TurboTax.
The following link provides CRA information on claiming Convention Expenses:
https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/sole-proprietorships-partners...