I think the key is to find new homes for the items that seem to live on the table. New
permanent homes and then develop the habit of putting them there. It takes some time and may take a few rounds of "new" homes before it becomes routine.
Papers, for example, used to be the main issue for us. I had too many "homes" for papers and they inevitably ended up wherever someone left them because they couldn't remember where they were supposed to go. Enter "the tray". DH has an old metal tray that he likes. It was clutter to me, but since he really liked it we brainstormed on a way to make it useful (thereby changing its clutter status). "The tray" is where all incoming papers of any sort go in our house now. It is located next to the computer where I do finances every week and I flip the whole tray over every Tuesday morning to empty its contents. I go through each piece of paper and take care of it, if possible, right then and there. Most are finance-related, which is what determined the location, but even DD's school papers and my "oh, I want to scrapbook that" stuff goes there (and so on). Everyone in the house knows where to put any and all incoming papers now. No questions, easy.
Also, what someone else said upthread, we commit to eating every single meal at the table. Placemats help, too. We are a family of three and have four placemats at the table. Those four areas are always clear!

Our table is big enough that DD can do art projects or homework at either end of the table and leave the placemats alone. If the project requires more space, she (or we) can move the placemats (usually by stacking them all on top of each other) easily enough. She knows we eat every meal at the table (and she loves food!), so she returns the table to meal-ready status when she is done. She has grown up this way, though, so she doesn't really know any different. KWIM? DH & I are the biggest offenders and required the most "retraining"....
