This will most surely upset the theater, but sneak in your own candy. By sneaking in your own candy you won't feel as if you just wasted an additional twenty dollars on top of your already ridiculously high admission ticket prices.
Step2
Pick your favorite seats. Personally I like to sit smack dab in the middle, but I understand we all have our preferences. Regardless, if the movie truly does suck, you don't want your poor seats to add to the problem.
Step3
The "please silence your phone" message has played, the previews are done, the lights have dimmed and your movie is about to start... first tip. Don't nitpick.
By nitpicking we're finding reasons not to like the movie. We're not even giving it a chance and so we're saying "Hey, here's $15 bucks just so I can tell people all the reasons I don't like this movie!"
So what, a line of dialogue was cheesy. Not all movies were made specifically for the theaters. Some movies like Spider-Man and X-men (Frank Miller's 300 even) obviously have their comic book fans to please, also. That cheesy line that you're letting interfere with the rest of the movie, might be straight out of the actual comic book. Meaning, it was put in the movie for the comic book readers. Not you. Get past that and watch the movie.
Step4
Watch it for what it is. A summer blockbuster.
Huge expensive movies released during the summer months are meant (for the most part) to simply entertain. Enjoy the graphics, the famous actors along with their idiosyncrasies and most likly, since today's summer blockbusters seem to all be adaptations, the big screen version of something we enjoyed in a different medium.
Tips & Warnings
If you're into following a certain celebrity or celebrities, pick a movie with an Actor/actress you enjoy. This way, odds are you don't have a problem with the acting. Plus, you get to see more of who you like.
If you like special effects, pick the movie you go see, based on the special effects in the previews. If they're showing them off, then they probably spent a lot of time making them worthwhile.
Avoid movies that seem like they're just trying to milk money from what's currently popular. Unless they have big names signing up don't count on them to be taken seriously and being handled with the care they need. Will Smith? Cool Peter Jackson? Cool. Andy Hershingburger? Who's he? My point exactly.