As stated before, you're going to need an outdoor antenna, mounted nice and high, to have the best chance of hearing the ISS.
As for waiting, there are several ways to cut that down a little. Either use one of the many online orbital predictors, or use software such as NOVA or Satscape to let you know when the ISS is going to be over your location. One tip - the higher the Station's elevation, the greater your chances. This article from our wiki has a few of these links (note that anything in blue is a link)
SATCOM - The RadioReference Wiki
Also keep in mind that the ham station is used, apart from scheduled school events (which would provide you with the best chances, if the Station is visible from your location during the event), when and if the astronauts have the time. This means that even though you might have a good pass, the astronauts could be in sleep period, or are very busy with station work. To that extent, it's a catch as catch can basis.
Oh, and they've been known to send verification cards for reports. Even better, if you happen to hear scratchy sounds, they're sending pix using a mode known as Slow Scan TV. We have links in the wiki for that, too. You would be wise to keep that software handy if you know you have a pass coming up.
HTH and GL...Mike