As investors, at what point can we deduct "Business" expenses?

[Account Closed]

Good Morning All!

I now have 3 properties under my belt - all from 2018. I am testin for my Sales Agent License tomorrow and am constantly looking for ways to invest my growing my business. I'd like some simple guidance on if the following types of expenses can be written off given my current level of activity:

1. Bigger Pockets Membership

2. Misc REI Memberships (i.e. Rentometer.com)

3. Seminar Costs including related lodging/mileage

4. Mileage to and from Rental properties (out of state)

5. Cost to obtain RE Sales Agent License

Thanks!