How do volunteers for humanitarian work could do their job efficiently and at the same time have deep emotional understanding for the victims?

First thing for the Humanitarian volunteers is to know who they are addressing, who are their target audiences. After that they should understand the problem of the audience.

When the objective is made clear then sort out the alternative solutions which may include training, workshops etc based upon their need.

One thing should be clear they should deal with their audience politely and with courtesy.They should make them realized that they are there to solve their problems.