Develop the idea of the game. It must be interesting, and for a wide range of Internet users. It is useful to analyze games, not only domestic but also foreign.
Then work the mechanism of the development of the game, which implies perfection of character, and the presence of a generated line of development and changes of the project.
Hire a team of developers, outlining the task. Decide the type of your project – whether it's a browser game or requires download and installation of the client. This is a very important step, because your choice depends on how the process will be the creation of the project. If you choose the second option, the exercise plan will be much more difficult than in the case of the browser game, however, the field activities for the realization of your idea is much broader.
Developing a "rough" version of the game, it is necessary to conduct open testing. This will allow to detect buggy and promptly correct them. And will help you gamers to test the product. Their opinion is no less important than the opinion of experts, because the game is primarily being developed for "mere mortals".
In order for the game to bring you income, consider the mechanism of its monetization. This can be a special game currency that is bought for real money, unique equipment, purchased exclusively for this currency, pay and other bonuses. Unique things should be much better than ordinary people to succumb to the temptation and eased their wallets.
The last issue that should be addressed is financing. After expenses will be enough – and the need for the server rental and the services of programmers, developers, and other personnel, and creation of the official website of the game, and so on. Of course, you can pay it all yourself, but you can attract to your side investors. However, equity capital is preferable, since in this case the control of the project will be in your and only in your hands.