First, let it do an initial fix. Install GPS Status & Toolbox from Play (or don't, use Maps application you already have), go out, enable High precision location (if using Maps, tap on My location button) and wait for a fix. It takes around 5 minutes, if device's GPS wasn't initialised. If devices GPS was initialised but can't get a fix, I suggest installing GPS Status and check the number of available satelites.
osmand uses OpenStreetMap, so you may try with that.