I have made just one 2d game for Android, that had an insignificant number of downloads.I would like to create a second project that results in a better game so I tryed to join a team.Result: the team had an impossible game idea. After I started my on team(profit division), but everyone left.Now I thi about create a game by my own, maybe hire some freelancers for 2d/3d art.But I am confused because the Android Market has 400k apps and I don't know how a solo developed app will become visible.I have some 3d game ideas, but I don't know if I can make it by my own. Formerly the problem was that I didn't know how to make a game.Now I know how to make a game, but i don't know how to make a successful game.

I'm sorry, but I don't see any questions in there. Rather than a technical question it looks like a rant about marketing, team building, designing a game, a future mobile product, and more. I'm moving this to the Lounge.

You are touching on several items, each topic is a better fit elsewhere on the site than where you've asked it. Feel free to ask more specific questions in the relevant area of the site.

The Business and Law area of the site has FAQ entries and discussions on market research and marketing. It is also a good place for discussions about who to hire for specific roles.

The Mobile and Console area of the site has FAQ entries and discussions on building mobile games and specifics for the mobile space.

The Game Design area of the site has FAQ entries and discussions about turning mediocre design ideas into funner design ideas.

The Lounge is a good place if you want to talk and commiserate about the difficulties and frustrations of game development. Since that seems to be the best fit for your post, I'm moving it here.

In direct reply, yes, game development is hard. Good projects often die prematurely. Good ideas often cannot be brought to market due to limited resources and from frustrating business decisions. The world of business is harsh. I'm sorry to hear of your troubles; it is difficult to watch others struggle, harder still to be the one struggling.

Looks like there's a mix of Business and Production questions in there.
Business: what platform, how do I deal with market glut, what game should I make. What people do I need to run the business. Planning the business finances out to 5 years. Revenue stream.
Production/Mgt: what people do I need to make the game, how to make the game efficiently. Planning the project, scheduling and budgeting the game project.

I'm sorry, but I don't see any questions in there.

I see the question... (not well stated though)

OP wants tips on making a successful game, as the next step after knowing how to make a basic game (worried that the market is over crowded and too competitive).

Well no easy answer. ie Knowing how to make a successful game is about experience, skills development, creativity and imagination.

Try and see if you can get a job with another more stable team, where you can learn as you work and through years you will begin know how...

I suppose you know a bit of everything (programming, game design, artist... ) because you didn't state your specific skills set

For many people its not an overnight thing, its a gradual learning process