3gstore.com is a great place to go searching for antenna and booster kits. Wilson Electronics is also another great resource to check into. All you need is equipment that is VZW 3G or 4G LTE compatible.
Start with doing a site survey. By accurately identifying what your current signal strength is and by doing a few simple tests in and around the area where you use your device, you will be able to predict whether an antenna or amplifier will improve your device's performance before you order expensive equipment