onto a good thing

*onto a good thing

having found something useful, promising, or profitable. (*Typically: be ~; get ~.) This is a great scheme. I know I'm onto a good thing. I'm onto a good thing. I'm sure I am.
See also: good, thing

onto a good thing

mod. having found something that is to one’s advantage, such as something easy, profitable, inexpensive, etc. I think that Bill got onto a good thing when he opened his own store.
See also: good, thing