Quickly resume playback on a locked iPad
If your iPad is set to autolock after a few minutes -- a common setting often imposed by your company's EAS or MDM policies -- and you want to adjust the playback volume for a movie, podcast, or song, or pause the playback to take a call, you don't need to enter your password to get to the controls in the Videos, Music, or other app in use. Instead, double-press the Home button to make the controls appear on the lock screen. On an iPhone, this also gives you a camera button, but not on the iPad.
Use a USB keyboard
I find the onscreen keyboard very easy to use, though it took a couple weeks to achieve that comfort level. But there are times you have a lot of typing to do, and a physical keyboard is the better option. I normally keep a Logitech Bluetooth keyboard in my travel bag for such occasions -- it's light, it has a protective cover that doubles as an iPad stand, and it holds a charge for a month or more. Other users love the ZaggFolio.
But if you forgot that Bluetooth keyboard, you may not be out of luck when you need. USB keyboards do work with the iPad, under two conditions: You have an Apple Camera Connection Kit to connect them through and their power usage is low. The iPad won't work with USB devices that draw too much power from the iPad, so if a USB keyboard doesn't work, try another one.
Extend the battery life
The iPad gets nine hours of battery life or more -- just as Apple promises. If you're a laptop user who has learned the hard way to cut the vendors' battery-life estimate in half, you don't have to do that for the iPad. But there are a few ways to push that battery life to 11 or more hours -- and prevent it from falling below nine hours.
The biggest battery life variable on the iPad is its set of radios: 3G (or, on the third-gen iPad, 4G), Wi-Fi, and Bluetooth. The iPad's iOS is good about putting these radios in low-power mode when not in use, so I routinely leave them all on. But if you want to stretch your iPad's battery life, such as for a trans-Pacific flight with no power source or an all-day seminar in some remote resort, turn off the unneeded radios in the Settings app. (Turn them all off by turning Airplane Mode to On.)
If you're traveling in an area with only GPRS or EDGE service -- the status bar's cellular icon will switch from 3G or LTE to a circle or E -- turn off the Cellular Data switch in the Settings app, or go into airplane mode. The iPad uses much, much more power for such sub-3G cellular connections and can end up reducing your battery life to just six hours, as I once discovered in a trip along California's Interstate 5 highway. By contrast, streaming a video over Wi-Fi for an hour does not noticeably shorten battery life, so it's really the cellular radio you need to manage for power savings.
If you have a third-gen iPad, turn off the LTE portion of the 3G radio in the Settings app's Cellular Data pane; LTE consumes much more power than 3G, which is why the third-gen iPad's battery is bigger and heavier.
The other big consumers of battery power are the CPU and graphics circuitry, but you have to be doing sustained gaming or visualization via apps that push the iPad to its limit. Chances are you're near a power source in such cases, so plug the iPad in. Just remember that the iPad needs a 10-watt or better power supply, and smartphone chargers, older computers' USB ports, and many powered USB hubs don't deliver that.