When you are clear why you want to travel and know where  you want to go then consider what you want to see and do while you're there.  

Consider that many museums need to be booked in advance and there can be long waits to get in.  Check your itinerary to ensure you have time to see what it is you want to see.

There can also be special events you may want to experience near your area so check to see what is happening in your travel area while you are there. 

The web is a great place to discover 'What's on in Paris'  You can then look up dates and find out what events are happening according to your interests.