How to manage the media content of your Apple mobile device, with minimal fuss...
Sometimes the Sync function in iTunes can get a bit complicated if you are managing multiple media types, or if you have micromanaged your Music library but can't remember exactly how you have your Sync settings set up. Thankfully there is a little known option in iTunes that circumvents your Sync options and allows you to simply drag-and-drop items from your media library to your device.
Firstly, plug in your device and wait for it to appear in the left navigation panel. If you are running iTunes 11 and cannot see the left panel, just click the "View" menu at the top and select "Show Sidebar".
Once you can see your device appear in the left panel, click on it. This will open up your device management option in the main window of iTunes. It should default to the "Summary" tab, but if not select this tab at the top of the main window (Note: this window is also where you usually manage your Sync preferences, i.e. clicking on the other tabs will switch the main window view to the appropriate data preferences). With Summary selected, scroll down to the "Options" section and select the "Manually manage music and videos" checkbox.
With this option selected, you can now simply open any section of your iTunes Library and drag and drop items from there onto your device below. So if you import a new Album either from CD or by purchasing from the iTunes Store, you can simply plug in your device and add the Album to your devices media library in one quick action.