Rachel Gibbs, over at Initial State, has written a great tutorial which gets a Pi Zero online via a mobile data connection. She’s added a GPS module to the FONA board and then powered the lot using a small LIPO battery. The system streams to their IoT service. You can read the full tutorial here. If you’re in the States, you’ll probably be looking to go to Adafruit for some of the bits. If you’re in the UK, Makersify is probably your best bet for everything except the LIPO.