Another thing to do, and it's not obvious, is to uncheck the "Automatically install new apps" option. When this is checked, if you download an app to your iPhone, it will download itself onto your iPhone the next time you sync it, and vice versa.
You will find this if you connect your iPad (and your iPhone afterwards, because you will need to do the same for both devices) and wait for iTunes to open. In the main screen, choose Apps, and then look to the bottom of the list of Apps that are shown. Underneath that list you will find the box to uncheck. It seems checked by default. If you do this with both your iPad and iPhone, it will prevent apps from automatically syncing to both devices.
When I did it, I had to do it a couple of times however, because for reasons known only to the abomination that is iTunes, it seems to reset itself before finaly getting the message.
I hope this is helpful,
Fred