So, "my job is easy" is "madali ang aking trabaho", but what about if the sentence is negative? Does the rest of the sentence remains the same? Is it "Hindi madali ang aking trabaho" ??
Correct.
You could also say Hindi madali ang trabaho ko (My job is not easy) OR Mahirap ang trabaho ko (My job is hard). Both of these sentences are a bit more colloquial sounding.