For example, you can type in uppercase by double clicking the Shift key twice quickly. To turn off, just click the Shift key again.
And to type a special character like #, you can press and hold the #+= key and then slide to the desired character. That allows you to continue to use the normal alpha keyboard afterwards.
Finally, to use alpha with special characters, such as ~ , press and hold a letter and other alternatives will appear. Just select the one you want to use!
For more iPhone tips, check out this helpful tip sheet from Apple:
One Cool Tip.com
Daily Tips for a Cooler Life!