Some may say wait, and call. I prefer to call immediately after getting the message. I'd try to be as nice and pleasant as possible to the service rep, and ask if there is anything else required of you before being approved. If they say you're denied, ask if your application can be reconsidered. Also, try to get information on what "negative" information rendered the denial.
Just don't sound "needy". Don't specify any particular big purchases you are looking forward to. I would say something to the affect that you need the card for frequent travel expenses and you like the idea of the rewards...etc.
***From ashy to classy***
