1. The Movie Itself
This one's probably the most important aspect if you want to enjoy a 3D movie and I'm very surprised to see that a lot of people seem to ignore this fact when deciding to see a movie in 3D. As a result many seem to have some kind of grudge against films in 3D which to be honest is something quite sad since 3D in movies does have a future in the industry. Horror movies for example are the prime example of 3D that's going to be not only rubbish but also completely boring with things coming right at the screen without adding anything to the story or the whole experience. Same thing happens with tons of kid's films (such as Spy Kids 3 and 4) in which 3D is used mostly as a gimmick to gain kid's attention. The only exception to that rule (in kid's films at least) will be with animated films since they're animated mostly on a computer which allows for an easier conversion. The 3D will look much better than in live-action films and in some cases it does help to involve you even more in the movie itself. Another thing related to this is that not all post-production 3D movies will be bad, it all depends entirely on the director of the movie and on how long they took to convert the movie into 3D. Guillermo del Toro for example personally supervised Pacific Rim's 3D conversion to make sure it will look well, making sure that they'll take enough time to make it look good. The Avengers is another example of this, since Joss Whedon took time to film certain scenes as a 3D movie to make it look better once the conversion is made. So if you're not sure if a certain movie did a good job with the 3D conversion a little digging might save you some money. 3D is still on a long way to go if it wants to be something other than just a gimmick, but just like color and sound movies were considered a gimmick on their time we might have the future of cinema right in front of us. We just have to give it a little chance.