These tips may be found elsewhere on the web already, I’m just archiving this info I put together a while back into a single repository in the form of a blog post.
Tips for both iOS devices and iOS simulator
Firebug for iOS
View Source of a page
iOS 8+: install an iOS 8 extension like the one called View Source. There are several extensions to choose from. The View Source one may be best as most popular, well known. Or you can also choose the other option for older iOS versions.
Tips for iOS simulator
Set up camera roll to be able to use photos and videos for testing
See: How to import photos into the iPhone Simulator — Aptogo. In general, drag & drop photo into simulator and then tap & hold to save image in simulator will add to camera roll for later use. See the linked article if you need to bulk import photos into simulator. NOTE: on simulator, you may lose the photos when you do an iOS “Reset Content and Settings…” command. No issue on device unless you specifically delete photo or do a factory reset.
For videos, instead of photos, see How do I get video into the iPhone simulator camera roll in iOS 4.2? – Stack Overflow. NOTE: on simulator, you may lose the videos when you do an iOS “Reset Content and Settings…” command. No issue on device unless you specifically delete video or do a factory reset.
Tips for iOS devices
Debugging mobile and tablet websites on iOS – on Windows or locally on device
Tips on mobile and tablet device testing shared usage and remote testing outside corporate network
Sharing bookmarks and photos across devices
If you use an Apple/iCloud account across the devices (This might work on simulator iOS 7/7.1+ if you sign in to iCloud from simulator and then do a Debug > Trigger iCloud sync, although I haven’t tested it):
The photos on each device (if not existing photos, then new photos taken) will be accessible across devices via the Photo Stream section of Photos app. And deleting photo locally in camera roll of a device won’t delete it from the Photo Stream (for that device and all other shared iOS devices), so you have to specifically delete from Photo Stream to delete across devices, the camera roll is treated separately from Photo Stream on each device, so you will notice copies of what you have locally on camera roll also in the Photo Stream that’s available across devices. NOTE: that the Photo Stream (for iOS 6-7.x) is temporary storage, and to make it permanent on each device, you have to save it to local system (device/simulator) before it expires in 30 days (I forget, but the system may copy the photos you’ve previewed to your device after expiration rather than let it disappear from the stream). The iCloud Photo library in iOS 8 is different though with it being permanent storage.
Creating a bookmark on one device will automatically sync (if enabled, by default) them to the other devices using same account, so you don’t have to set up bookmarks/bookmarklets individually on each device.
Recording actions against or test session of iOS physical device into a video
For iOS 8+ only, but see Record your iOS Test Session with QuickTime | Daniel Knott
Tips for simulating iOS device in browser via user agents, etc.
Device screen sizes for testing mobile and tablet views of a site and user agent tools