A new state government campaign is warning consumers about deceptive marketing practices that some for-profit schools use to attract students. For-profit schools often market subpar programs to veterans and low-income students who depend on federal loans to attend, said Massachusetts Attorney General Martha Coakley. Recent studies show that for-profit schools together spend billions a year on recruiting and marketing, Coakley said. But she said studies also show 47 percent of federal loan money that goes toward for-profit school tuition will end up in default. Coakley’s office said the consumer initiative also includes free training across Massachusetts and that more than 3,500 people have taken part.