This is a single tip to make billions in gta v single player.The first step is to ignore all the assasination missions for Lester until the end of the game.If you pulled the big one right (option B, first driver Martinez,random event,second Karim,first gunman Packie McReary or Chef,second Norm Richards.In the end Trevor and Franclin will have 36.000.000 and Michael 38.000.000.Then do the assasination missions and start to invest in the stock market.FULL DESCRIPTION:www.ign.com/wikis/gta-5/Assasination Investor.After seeing the Assasination Investor in ign.com you do the missions.If all end up well then you will have 2.1 billion.After that focus on Michael and do the Epsilon Programm missions.In the end if chosen to take the money,you will gain 2.1 million(worth the money).For these missions you must also watch a guide this time in youtoube(especially with the cars).In the end you must complete a random event (give an investor a ride to the airport) and after you do that he will advise you to buy certain stocks (I think tinkle,but anyway he will tell you).When the stocks go up,sell them and there you go.With all this money,you can buy everything(properties and vehichles) and still have a lot of money in your pocket!