Typically the front of you case will already need at least one of the USB 2.0 slots for multimedia or USB connections.
But if it doesn't include a multimedia manager you may want one to handle various Memory Cards (cameras, phones, etc). And decide if you want to use an external 5.25" or 3.5" bay.
If the case doesn't include a multimedia manager then something like this
Rosewill RDCR-11004 5.25" will use at least one USB 2.0 as well as a USB 3.0 connection and a 5.25inch exposed bay and 2 Molex connections from your PSU:
Just do a search on "internal USB 3.0 hub" and look at the various options to pick one that suits your needs.