The iPad's onscreen keyboard approaches the dimensions of a full-size keyboard (in landscape orientation, at least), but the layout of the keys is not completely standard. One of the most maddening things about the default keyboard is that it lacks an apostrophe key. I'm used to the apostrophe's position on a standard keyboard—all the way to the right just before the Enter key. I keep reaching for it with my right "pinkie" finger and end up hitting the Return key instead. I can enter an apostrophe from the "symbols" keyboard, which is accessed by tapping on the ".?123" key. Fortunately, there's a quicker way to do it.
From the default keyboard, press and hold the comma key. When the blue alternate key pops up above the comma key, simply release the key and an apostrophe is entered. You don't have to move your finger to the blue key to select it.