If you have a brilliant idea - great! But it is just one percent of what you need to become an inventor. Thousands of people have good ideas every day, and just a very few of them turn into inventions. Of course, not every idea that comes to your head is worthy to become an invention. But if you think your idea is useful and workable, you should consider developing it further. If your invention idea can be turned into a product, you can hope to earn some decent sum of money with that. However, in order to become a successful inventor, you'll have to work hard.
Don't give up! The good news is that you do not have to do everything yourself. If, for example, for creating a prototype of your invention, you do not know how to create a computer model you would like to use, ask a specialist to do that. If your prototype requires some wooden or metal parts and you are not a DIY guy, order those parts.
Do I have to keep my idea in secret?
While working on your invention you should not be mortified with fear that someone will still it. It is very hard to steal an undeveloped idea. And nobody bothers for stealing something that is not a proven success yet. However, you really don't want to talk about the precise principles of the work of your new device with a known competitor.
Avoid publishing any information about your invention in any public media including the Internet as public disclosure can jeopardize the patentability of your invention in many countries. However, you can talk about your invention in general terms in order to find out if it is going to be of any interest for a potential manufacturer, or just seeking for an opinion/advice from your friends/relatives.
To patent or not to patent?
When you are done with elaborating on the concept, design, and prototype of your invention, do not hurry to apply for a patent. Patenting procedure are usually complex, they last for some months, sometimes even years, and they are subject to a number of fees. Analyze one more time your invention, check if it is worthy of patenting, think of possible improvements.
On the other hand, you can go for professional help. There are many patent attorneys that help inventors regarding this procedure. If you're looking for a one, then InventHelp could help you patent process and market your product as well. You can read more about this company here: https://www.crunchbase.com/organization/inventhelp
Some improvements are unnecessary and you could reserve them for the second version of your product. Don't try to reach perfection. It is usually impossible and you don't want to waste your lifetime and fortune chasing it. Talk to a qualified patenting attorney and take a calm decision if you should apply for a patent or not. For more detailed information on patenting check my lens on How to patent an idea
Creating a product is not the end
When the product is ready, there is still a long way to succeed. At this stage, you should consider marketing your product, looking for sponsors, investors or partners. Try to make some initial marketing yourself. Remind, it is not necessary that the better invention, the more money you get.
A proper marketing approach can make a difference, but if you decide to address some marketing company, chose it with a lot of care. Treat your invention as a business. Don't think that any invention will make you a millionaire, but there are many even little inventions that are pretty much worthy of your efforts.
Don't try to seduce potential investors by charging too little price for your product. It will just provoke suspicion. On the other hand, be frank with yourself and don't expect to be able to market a totally useless idea at a sky-high price.
You don't have to be Einstein
As a final remark, I would like to state, that, to succeed, you don't need to invent something revolutionary. If your idea solves little but real existing problems at the rational expense, it, usually, has great economic viability. So, with a bit of imagination and enthusiasm to be useful to people, you will certainly be able to create a successful invention.