Even though you will find more detailed help on our forums when/if you are ever in the position of switching from iOS to Android, that doesn't mean that Google won't try to make it easier too. In fact, they recently published a new guide which is designed specifically to help users make that transition from Apple-land to Android heaven.
This guide includes quite a few handy tips including transferring photos, transferring all of your contacts, setting up your email and messaging and much more. The landing page for this guide is appropriately called AndroidSwitch, and here is a link below.
Remember though... if there is anything they missed (which is probable), be sure to ask here in the forums or do some digging, because we can answer just about any Android question you can fathom.
Source: AndroidSwitch