Check out the great interview with Dick Costolo, the CEO of Twitter. You just can’t get any better update about what Twitter is about now, where it’s heading and get a clue for yourself about what might you do wrong about the way you’re using it. And btw Dicks’ sense of humor is just out of chart - you’ll love it! 
Twitter CEO Dick Costolo: The Full D11 Interview (Video) - Mike Isaac - D11 - AllThingsD
My outcome of it is that even though Twitter has changed significantly it’s still about sharing information real time and hence when you’re planning your app promotion on Twitter take into account:
Day and time you’re sending a tweet and a time zone of a country you’re targeting your message
Current popular tags that are relevant to your app
People are skipping through many tweets and so make sure they can get your point right away
Add call to action to your tweet
Think of time sensitive promos
Twitter CEO Dick Costolo: The Full D11 Interview (Video) - Mike Isaac - D11 - AllThingsD
My outcome of it is that even though Twitter has changed significantly it’s still about sharing information real time and hence when you’re planning your app promotion on Twitter take into account:
Day and time you’re sending a tweet and a time zone of a country you’re targeting your message
Current popular tags that are relevant to your app
People are skipping through many tweets and so make sure they can get your point right away
Add call to action to your tweet
Think of time sensitive promos