There are a couple of things I need to establish before I continue. First off, the best most of us can do when it comes to designing games professionally is to simply make a living. Dreaming of creating a smash hit that makes you very rich overnight is unrealistic on several counts. First off, publishing a game places you squarely in the publishing industry. And the publishing industry has some obvious limits. Perhaps an illustration is in order. Let us take World of Warcraft as an example. This game started in the publishing industry but it has crossed over into online service territory, the type of position facebook and google enjoy. This is obviously where the big bucks lie. WOW did NOT make this move by accident! Boardgames, on the other hand will probably forever occupy a similar (but lesser) position in publishing to novels and cookbooks, way below other parts of the publishing sector, the movies, the music etc. I'm not trying to sketch an overly gloomy picture, but think a bit about the publishing industry before you dive in. On the one hand you have the odd housewife that became a millionaire by publishing her recipes, on the other you have a publisher burning their excess book stock in an abandoned canal outside Buffalo, New York. Success is quite possible, but keep your expectations level headed.
Now, you would not be here if you were not a board gamer yourself. So you can bet the other people on this site also own stacks of boardgames, they always will and they may be the first to buy your game. If you come up with something good. The sooner you start to work with the community, the better. We test games because we know that the ideas we have on paper may look ground-breaking and brilliant, but it is often a shock to see just how impractical and counter-intuitive those ideas become when real people test them. This is why open source software is the next big thing, because of the sheer number of people involved. If you are carefully keeping your ideas under wraps you are missing out on the input of others who would have shared with you more than what you were trying to hide from them. Be warned though, cross-pollination of ideas is inevitable. But this is probably more beneficial in the long run. Once again, we are all gamers, we are collectively mostly interested in buying games that are better than what we already own.
So here is what I suggest: try to design at least one boardgame with the aid of the community on this site. If you hopefully now have level headed expectations instead of the dream of earning millions from your wunder game, and you accept that you still can design many games on your own in the future, what is the worst that could happen?
You raise an important point: before starting a open boardgame design some ground rules are needed. Otherwise what should have been positive influences can end up hijacking the game development.