First of all keep it very quiet. Share the idea with very selective people whom you trust. The word spreads quickly so it is important that you don’t go around telling everyone about your million dollar idea. As a general rule, always disclose the minimum necessary details so you know that you have most control over your idea.
Get your idea patented. This is the first legal thing or process you need to undertake in order to protect it. Contact the US. Patent and Trademark office and see the how a patent is filed. A patent gives you an official right on the idea, where no other business, entity or person can pursue it until notifying you or collaborating with you. The cost associated with patenting is relatively higher, including filing and legal fees. Make sure that you can present the idea in tangible form i.e. your idea must give rise to a new invention or design, something not present in the market.
A non-disclosure agreement is another way to protect your idea. If you feel that your idea can bring a certain change, and in order to do, you consider the option of contacting or keeping resourceful people in the loop, you may first sign a non-disclosure agreement. This way you can regulate the information you want others to know.
Take legal advice on the matter. This could be a fundamental procedure for beginners as the legal person will have all the knowhow about your concerns and can easily protect your interest. A lawyer can further guide you regarding the need to obtain a business license. This way business people will take you seriously and may be inclined to work with you or even fund your idea. The lawyer will also help you with questions on patents, copy rights, trademark etc.