With time it can happen you have a bunch of installed apps on your Windows Phone 8 powered phone you never use anymore, I suggest you to remove them to free some of the storage.
If you are on a certain data plan on your mobile provider, and don't want to exceed it, you can set data usage warning and a limit which can help you save some of your money.
Let me show you how to add a Google account to a Samsung Galaxy SIII so you can read you Gmail email, download apps from the Play Store and synchronize you Google Documents.
The new Nokia Here Maps have an option that enables you to download maps to your iPhone or iPad via Wi-Fi, so there won't be any data connection needed the next time you will be using the app.