How can I care of licenses?

Hi to evryone , I'll like to ask you , if somebody wants to try to build a game ( e.g. a graphical or textual videogame ) , how can be sure to don't infringe any other license ? Is there a solid line to look at ? For examle if the game's character will be too close at the look of some already existing hero , or the story seems like a promoted book , or film ... How can I be aware of ? Any character must not to use names , looks , story-like any popular - familiar hero ? Is a parody version accettable ? This just to don't find myself in a debt lol .

Ps : Thanks for all you advices , and to all HN staff:nice stuffs! ( sorry that enghlish is not my native language ) .