(1) I designate a particular physical space for Deep Work—one with a couple of qualities similar to the space one might create for meditation (“a quiet space where you won’t be interrupted”). However, because meditation, for me, usually takes around ten minutes, a bedroom with the door closed suffices. For Deep Work, I try when I can to use a space outside my home, such as a library or a coffee shop (the Starbucks where I am is usually quiet enough; other coffee shops are not).
(2) To get started, I tell myself I only have to work for 25 minutes. Often once I get started, I can get into “the zone” and work for 45 minutes (sometimes longer if my schedule allows).
It all boils down to the mental preparation you put into your routine and the "why" of your wanting to do the deep work. If you have that clarification in your mind, the rest is easy to take care of.
Sometimes, if the train is not too crowded, I actually do the deep work while on commute. Sometimes Ido it before so Ican enjoy reading on the train.