Chris offers some sound advice and I am going to add to it a bit.
First of all, make absolutely certain that what you've come up with is worth marketing. The industry is swamped with folks that believe everything they thing up is the next million dollar success story when move than 95% of it is garbage and worse, replication of existing material (yes, even when you come up with it independently). This is one of the reasons I emphasize historical citation when you develop an effect you want to market (or include in a book). Start with what inspired you and trace that effect's history back and so on, so an evolution can be seen. This is very important when it comes to an "improvement" to various bits.
Yes, historical research can be a pain and quite expensive; you either have to buy the books or have access to private libraries that can put you in contact with said references. My recommendation is to join the Magic Castle and make annual pilgrimages that give you time in it's library (so far, no one has screamed "copyright" infringement and "exposure" when it comes to such) . . . I used to live in that room.
Aside from what should be obvious, citations of this sort will impress the bigger names and with certain one's such as Burger, Knepper and Maven, it will go a very long way in that you will not come off as being another kid with a pipe-dream. (These three are not known to give any kind of kudos to anyone, so when they do it really means something).
The other thing you need to consider is manufacturing. So many come up with great pieces but never think about how much of their time it's going to take to assemble gimmicks or whatever else goes with the effect. This is a major concern if you are pitching a big distributor like Murphy's. Oh! Don't expect to make a lot of money on your first 3-5 pieces, especially if you go through a distributor. Someone like Murphy's can move product once they accept it (which can take over 3 years to process), but they also want a below wholesale price when it comes to bulk orders (5,000+ pieces at times -- which reflects on your manufacturing issue).
Because of these little issues there is another route to take that's far fewer headaches; sell the effect's manufacturing rights to the distributor or whatever company for a flat rate + so many copies of the trick so you can sell them and of course a good rate for any future stock you personally buy. In some cases (once' you're a "name") you can get a minor royalty as part of the deal. In such cases it's up to them to get the quotes, reviews, and deal with the manufacturing details, etc. BUT, get yourself a damn good contract lawyer when negotiations come to a close. It's far too easy to loose all control over your material and too, you want the buyer to spell your name right on the packaging so they don't forget to credit the source (it happens far too frequently, along with some clown from the purchasing source putting their name on it).
To sell the concept you should have a simple video that simply shows the effect. There needs to be a non-disclosure agreement in place before hand; some means by which to prove correspondence as well as source. There's nothing I hate more than seeing letters returned claiming that a concept was not viewed and then three years later you see it on TV. . . plausible-deniability.
FINALLY. . . my strongest suggestion is that you NOT market the effect just yet. Save it along with a good dozen others that you have field tested, used in numerous performances (along with others) and then package into a book or DVD collection. You will get far more kudos and mileage when it comes to building your name recognition and appreciation by taking this route (just look at Jay Sankey). You will also want to contribute routines to chief magazines & newsletters including MAGIC, MUM, etc. with the goal of building your reputation; the stronger reputation you build for giving away solid material through the magazines or even other people's books, the more value will be given to the things you produce and thus, the more money you get from what you market.
Yes, it's a slower boat but it's a ride that has greater longevity.