The first step I would recommend is a patent search. Most of us know that many companies are dying to let you pay them to do this.
I have found that for a lot of my inventions, I am able to do a primary patent search myself without paying for it.
Here is an article that may be useful! Hope it helps!http://www.ideabuyer.com/news/how-to-conduct-a-patent-search/
The first thing to do is get a profession patentability search and opinion and NOT from a scheister marking firm, but from a registered agent or attorney. If the opinion is worth even $10 there will be dozens of patents found because it should be an element by element search that can NOT be done by google, but by a patent classification search.
The least amount of patents that were relevant for any invention I have found was about 15 patents. Unless you are patenting a new DNA string there will be dozens of art.
A proper analysis will discuss rejections under 102 (anticipation) and 103 (obviousness) rejections that can be brought by the USPTO. Over 50% of the searches I have done leave the patent application with only very narrow undesirable claims that have no marketing/licensing value.
I have done opinions for companies and that is the first thing they look at before going forward. I do patentability opinions for $500, which is the cost I charged at my last firm of $1700. The cost of a good search was $450 and thus I only charge for me to do the search and throw in the opinion for free.
This small amount is critical to map out the future of your product. ALL COMPANIES do a patentability search before patenting their own inventions to avoid throwing tens of thousands of dollars at law firm full rates down a black hole.