Present Simple or Continuous

We use the Present Simple
• for regular actions or events 
  I watch TV most evenings.
• facts 
  The sun rises in the east
• facts know about the future 
  The plane leaves at 5.00 in the morning.
• thoughts and feelings about the time of speaking
  I don't understand.
We use the Present Continuous
• at the time of speaking ('now')
  I'm watching a movie on TV.
• things which are true at the moment but not always
  I'm looking for a new job.
• present plans for the future
  I'm taking my husband to New York for his birthday.
Look at these sentences:
• I usually don't drink coffee but I'm having one this morning because there is nothing else.
• I often drive to work but I'm taking the train this morning because my car is in for repair.
• I'm thinking about dying my hair blonde but I don't think my wife will be very happy about it.
• My parents live in New York but I'm just visiting.
Notice how in all these examples we use the present continuous to talk about events which are temporary/limited in time and the present simple to talk about events which are habits/permanent.