How to Outsmart Google on Keywords ?

i have a real estate website which used to have more exposure when i started it, and my competitor was at low rank, though that was an old site. but before a few months, after some google major update, my website got completely out of searches, then after some blogging and updates etc, it came back but now the rank is very low. The same articles which ranked higher for some keywords are ranked very low. and my competitor who doesn't put anything special except for 3 or 4 sentences in a page for some keyword, he ranks very high????
I am at a loss, what happens when google does this to a certain site and ranks other sites higher which may not contain anything special.
Now i am making seperate pages for different housing schemes in islamabad, and going to put all real estate lisings for that specific society in that same page by making a table. but what about articles that contain information about that society? should i list them down in that page too or keep them seperate? how to make one page most important for a certain term in the eyes of google???
I hope people have understood what i am saying, so i need some seo help. thanks