The Present Simple is used for:

• regular actions or events
  He plays tennis most weekends.
  
• facts
  The sun rises in the east.
   
• facts known about the future
  We leave at 8.30 next Monday
  
• thoughts and feelings about the time of speaking
  I don't feel very well.

The Present Continuous is used for:

• the time of speaking ('now')
  Shh, I'm trying to hear what they are saying .
   
• things which are true at the moment but not always
  We're looking for a new flat.
  
• present plans for the future
  We're having dinner with them next week .

Look at these examples :

• I don't usually have cereals for breakfast but I'm having some this morning because there is nothing else.
• I often cycle to work but I'm taking the car this morning because it's raining very hard.
• I'm thinking about having my hair cut short but I don't think my husband will be very happy about it.
• My parents live in Washington but I'm just visiting.

Note 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