Ok, lets get to the getting. What makes a classic movie? I think it has to have at last a touch of all elements, action, drama, love, emotion, adventure and throw in a bit of sin for fun. There are movies that focus solely on a few of those and do very well, but dont in my mind reach classic status. To reach that status the movie has to have characters you can not only relate to but start to actually care about. Explosions and special effects (while cool) are only background to what is happening to the individuals in the movie. Star wars as a quick example cant help but suck you in as we can all see a bit of ourselves in each of the characters. Luke, naive but full of dreams. Leah, headtstrong and willfull. Han, carefree and lacksadical. Obi-wan, wise and full of knowledge. These are triats that we either shae or wish we had more of.
For me a classic movie is one that immeadiately after seeing i think about for hours and days, even if only to say "god that was an awefull movie", it makes me realize that even an average movie is stellar in comparison. As an example take 'Battlefield Earth' with John Travolta. Based on a great book, with good actors and action, and special effects. But i have never heard such a unanimous condemnation of a movie! On the flip side is a movie that you see and even years late you still like to watch and reminisce about with other people who have seen it. Cult movies are a prime example of this, not everyone likes them but those who do are very fanaitcal in thier devotion to it and tend to form 'cliques' of like minded people.
If you want a classic movie, look at what you already like and WHY you like it, did you like the charachter, were the effects mind-blowing, were the emotions genuine, touching and heartfelt? Look for these in other movies even if they may seem to be a bit out of what you'd normaly view. Alot of mediocre films may be seen if you try this approach, but when you find a nugget in the rough......suns rise, the sky falls and...well, its not QUITE that good but its still a great feeling! Alot of the classics that i now like i have seen because other people got them or i saw them by chance( up late, nothing on tv, 'oh well, may as well watch this, nothing else on' kind of thing) this taught me that you have to step out of your comfort zone as it were and try stuff that you wouldnt odinarily watch. Its not as bad nowadays but people still have a tendancy to pooh-pooh foreign films when alot of them have a cult follwing for a genuine reason. Good enough and a cult follwing can become a classic, and if its THAT good a classic can become a genre in itself. Akira (japanese anime movie) is a good example.
So, if you find out what you already like in movies, start hunting for that in other places no matter how strange, fringe films are a constant source of surprise and joy, as a alot of foreign films fom small production companys. Ask friends and family, they already know what you like and have seen alot of movies between them. Read reviews, look into genres that you wouldnt normally, im not a horror fan but was blown away by Wolf Creek (Autstralian produced Horror.) There is alot of dross to sort through out there but im sure you know how it feels to come across a movie that you know youll like for years to come if not your entire life.
heres a list of my movie classics in case your curious, in no particular order,
Men of honour, Full Metal Jacket, Heat, Ghost in the Shell, Cube, Logans Run, The Transformers Movie(80's), all of Hayao Miyazaki (japanese anime), Predator, Brotherhood of the Rose, JFK, Indiana Jones trilogy, John Wayne (all of 'em!), The Negotiator....I could go on for quite a while but im sure you get the idea!
Good luck and dont forget to look where you normally would'nt!