They're not entirely strangers, and chances are, you've already networked with them.
Otherwise, if you tweet them, it is likely you're responding to their tweets re: something else (not just blankly self-advertise or something).
One way I've seen it done well if finding a way to plug a portion of what you're trying to advert by making a perfectly valid reply to something they are saying.
Press Person "Ah I love space"
You "So do I. You should try (X-game themed in space), it really captures that mood well".
as opposed to
You "Try my game!!!1!!11! here's the funky UrL: "http://www.roxorzdaman.com/thatshittygameImade"
Edit: Thank god that URL does not exist...