My default approach is always: watch the movies in the order that they are released. My reasons are:

1. I want to experience the "historical" perspectives of the people who watch the films as they come out. An easy example of this is the Star Wars series. I haven't seen any of them yet (gasp!) but when I get around to do it, I will watch 4,5,6,1,2,3. This way, I'll get to see the supposed old-school magic first and then the new-school prequels that seem to disappoint many fans. In sum, I want to see things in the same order that those fans have seen.
2. While film makers usually make new releases in a franchise in such a way that new viewers who have no prior exposure to the franchise can get it, these film makers must have in mind the people who have seen the previous installments in the franchise. Thus, I believe that you can get more out of the new releases if you have seen things in release order, regardless of whether the new ones are prequels or sequels.

My default approach is always: watch the movies in the order that they are released. My reasons are:

1. I want to experience the "historical" perspectives of the people who watch the films as they come out. An easy example of this is the Star Wars series. I haven't seen any of them yet (gasp!) but when I get around to do it, I will watch 4,5,6,1,2,3. This way, I'll get to see the supposed old-school magic first and then the new-school prequels that seem to disappoint many fans. In sum, I want to see things in the same order that those fans have seen.
2. While film makers usually make new releases in a franchise in such a way that new viewers who have no prior exposure to the franchise can get in, these film makers must have in mind the people who have seen the previous installments in the franchise. Thus, I believe that you can get more out of the new releases if you have seen things in order, regardless of whether the new ones are prequels or sequels.