The leaks tend to be a consequence of their supply chain not being able to keep tight lips more than anything else. One approach to combat that would be to announce a product well in advance of production, but then you have announcements followed by six or more months of production ramp-up. Which is obviously awful.
Until Apple is able to bring much more in-house, which they can't realistically do in most cases involving manufacturing, the leaks are inevitable.
If you want to maintain the magic for yourself, though, that's simpler: don't look at Macrumors or what have you :)