I'm an independant contractor & I ride BART, bus, & Uber to get to and from my clients homes. Are my costs deductible? If so, where do I enter the deduction?

Yes, as an independent contractor, your transportation expenses to client homes are allowable business deductions. 

Here is where you enter in TurboTax On Line Self Employed:

Federal

Income & Expenses

Scroll to self-employment income and expenses

Scroll to business travel

Add each type of travel and your total expenses

For more information about qualifying business expenses, follow this link: Common Deductions for Businesses