5. An activity budget
This is where researching your destination actually makes a lot of sense. Look for fun things to do. If you just plan to visit museums, art galleries and other historical monuments it might not make a difference. But if you plan to do more adventurous things like sky diving, bungee jumping, scuba diving etc, you need to make a budget for it. Many adventure sports companies offer combo deals which end up being cheaper than usual. Shopping is another way to spend all your money. Make sure you take note of all these things.