Can i write off my mileage for my lyft and also my parking expenses and train rides for my main job or can i only do one or the other?

Do you mean you are a Lyft driver---or that you use Lyft to get to work?   You cannot deduct anything for the costs of commuting to work whether it is in your own car, an Uber or Lyft car, a bus, train, or plane.  

 

If you are a rideshare driver then you can enter your self-employment expenses on a Schedule C

https://ttlc.intuit.com/questions/2926899-how-does-my-side-job-affect-my-taxes

https://ttlc.intuit.com/questions/1901340-where-do-i-enter-schedule-c

 

https://ttlc.intuit.com/questions/3398950-what-self-employed-expenses-can-i-deduct

 

Tax Tips for Uber, Lyft, Sidecar and other Car Sharing Drivers FAQ

 https://turbotax.intuit.com/tax-tools/tax-tips/Self-Employment-Taxes/Tax-Tips-for-Uber--Lyft--Sidecar-and-other-Car-Sharing-Drivers/INF28820.html 

 

https://ttlc.intuit.com/community/charges-and-fees/help/how-can-i-apply-my-uber-discount-to-my-turbotax-account/00/27505

 

https://ttlc.intuit.com/community/account-management/help/why-isn-t-my-lyft-discount-being-applied-to-my-turbotax-account/00/27366