What is the name of your state (only U.S. law)? California
I am considering getting an immigration lawyer to help me obtain a work visa in the US. However, I am not sure whether I am supposed to consult a US lawyer or one in my country of origin. How does it work?
Both ideas you got in reply are good. A US immigration attorney would be a must; when you find them outside of the US they tend to be very expensive. It's now easy to work with an attorney located in the US even if you aren't, through phone, email etc.
Be VERY careful about hiring a consultant, advisor, anything other than an attorney. Too many people see their money and their dreams go walking...
You can use ailalawyer.com to find US immigration attorneys.