From a FAQ I'm working on (draft only):
Q: I have an idea that will save people/companies/the world millions of dollars each year. How do I make millions of dollars from this idea?
A: The very first thing you must understand is the Intellectual Property (i.e., protectable rights in your idea) is only one piece of the overall puzzle. Patents are often essential but rarely sufficient. It is absolutely imparative that, to realize any profit from your invention, it must be utilized in the marketplace. If noone makes, uses, or sells your invention, you don't make any money from it.
So, how do you get someone to make, use, and/or sell your invention? Unless you're already extremely wealthy, you'll have to convince someone else to take a chance on your invention. The shortest path to doing that is to convince some company to use your invention and pay you a royalty. This can work if your invention fits neatly into the existing business of such a company and provides a sufficiently large profit margin that they can make more money than they do now, even after paying your royalty. For this path to riches to work, your idea must be protectable. Otherwise, the company could just use your idea without your permission.
Another possibility is to form your own company and go into business making, using, and selling your idea yourself. The primary advantage of this approach is that you've already convinced one person that your idea is a good one -- yourself. The disadvantage is that it takes a lot of hard work and a lot of time, and sometimes a lot of money, to succeed in doing this. Having started and/or run successful businesses in the past is very helpful, but not always necessary. Typically, you'll have to convince at least one investor to contribute money -- typically in exchange for part of your company and a share of the profits. The topic of raising money for a new business is very far from intellectual property law, so there's not much I can tell you about that, except that you really should have the relationship between you, your investor(s), and the company carefully spelled out in a written legal agreement. In this approach, having strong intellectual property is very helpful but not always necessary.
The last approach is probably the least expensive and the least likely to produce meaningful income. Acquire whatever intellectual property you can in your idea (typically a patent) and wait for others to stumble onto the same idea and sue whoever uses your patented idea in the marketplace. One issue is that you still have to produce a patent on your idea. You can write it yourself, but unless you really know what you're doing, there's a substantial likelihood that your patent will have a significant flaw which substantially reduces its value -- perhaps rendering the patent completely worthless. You can have a professional write the patent application, but that requires some monetary investment. Some have had success in combining patent drafting services with investors by convincing a patent attorney to write a patent application for a share in future profits. However, most patent attorneys eventually learn that evaluation of potential earnings of proposed business models is best left to the other professionals: professional investors. In other words, in most circumstances, it's best to separate investment from patent drafting services.
Okay, let's assume you've found your path to riches and only care now about protecting your idea. Now, we can talk.
Every idea starts as a trade secret -- a secret which has commercial value. You protect them by keeping them secret, only telling people who haved signed an agreement to keep your secret to themselves, i.e., a Non-Disclosure Agreement (NDA).
If your idea is creative, like a writing, a painting, T-shirt designs, photographs, music, etc., you prevent others from making unauthorized copies with copyright protection.
If your idea is technical, you apply for a patent. In essence, you offer publication of your technical idea as adding something of value to the whole of publicly available technical knowledge in exchange for rights to exclude others from exploiting your contribution.
When you bring your idea to the marketplace, you want a name for the product or service so that people who like can identify your product or service when they say nice things about it. That name is a trademark. It allows you to prevent others from using names for their products in a confusingly similar way -- a way that would likely confuse consumers as to whether they're really getting your product/service or someone else's.
That's basically it.