Bf is unhappy with his job?

My boyfriend is currently an installations engineer at a local firm. He hates his work, and says that it is the disorganisation of the company, as well as ridiculous hours, travelling all over the place at short notice including overnight stays, and that he is underpaid for what he does. He has very little time to search for a new job around his work, but has been trying. Can anyone offer any advice how he can improve his situation? Thanks!