In response to your post, hopefully you have already conceived of your idea. That is the first stage of invention.
You need to decide what your idea is: is it a new invention- (device, process of doing something, material, etc)? Then it may be patentable.
Is it a writing, music, etc. Then go for copyright.
Is it is a design of the product or name that identifies you as the source of origin-then trademark.
I’m guessing it is a patent. Try to design a drawing or try to build it or have a factory build it.
The other thing you can do is search Google or Google patents. Try to see if your idea is out there before you waste money.
Then try to find a patent agent or attorney. The patent office maintains a database of them. Google it. Find one in your area. A patent agent would probably be cheaper as they don’t have a law degree but they are effectively the same as an attorney.
You can also represent yourself, but it isn’t a good idea, because its much harder.
Hope that helps.