This first thing people think when they come up with their big idea is that they need a patent. Maybe yes, maybe no, but you won't know if you don't do your homework. The very first thing you need to do is google your idea. If the search brings up pages and pages of similar products, you may not be the first to discover the need for this great thing. Do the on line searches several times with many different key words, you will be surprised what doesn't come up in the first search will come up in search number 25. Next, go to www.uspto.gov to do a patent search. This step can be daunting but you have to do it. Go to the patents section, then search both sections, patents pending, and patents issued. This again is one of those steps that will take some time. Use as many words as you can think of that may be part of whatever your idea is. If you can't find your idea in a web search or a preliminary patent search, then you're probably good to go to the next step.
I've made mention already that you need to create some kind of prototype to see your idea in real life. You need to know if it really will work. After you do that, you need to decide if you will pay an attorney to do a professional patent search or move ahead with just your research. Some attorneys will not file your application unless they do the search for you (you'll pay of course), as they have to represent you to the examiner at the patent office. They want to be as sure as they can be that they are going to get the patent issued.
You can do this yourself and for many things you don't need a patent. If you feel like you have a great idea that's not already on the market, get to manufacturing, producing, and selling your great product! You can do it. Remember, whatever you think, you're right!