However, the two applications do have their differences. FingerPrint requires OS X 10.6 or higher, and it has an option to "print" directly to iPhoto on your Mac. But before a printer appears in FingerPrint, it must be shared using the Print & Fax pane of System Preferences. Printopia supports OS X 10.5 or later, works with any printer (shared or not), and can send files from your iPad to a PDF or PNG file on your Mac (much like OS X's print-to-PDF capability). As of version 2.0, it also lets you "print" not only to iPhoto but to any Mac application, save files to any number of folders on your Mac, use any PDF Workflow on your Mac (such as e-mailing PDFs--click the PDF pop-up menu in any OS X Print dialog to see all your options), and configure printer settings. For all of those reasons I greatly prefer Printopia.
Another option exists, too, and it's even free (donations requested): Netputing's AirPrint Activator. But although it serves the same basic purpose of enabling AirPrint to use any printer your Mac can see, AirPrint Activator has a rather tedious setup process, and doesn't offer a way to print to DropBox or to a folder on your Mac.
Printing with AirPrint
Once you have either an ePrint-compatible printer or an AirPrint enabler set up, printing from your iPad is simple:
First, look for the Print command. Assuming an app has been updated for AirPrint support, this command is in there somewhere, although the location varies--sometimes it appears when you tap a button with the word Print or a printer icon on it, other times it may be in a popover that appears when you tap a Tools, Send, or Action icon. (When in doubt, check the app's help.)
Next, if this is your first time using AirPrint, or if you want to switch printers, tap Select Printer and then tap a printer name. The printer you select becomes the new default printer, meaning you can skip this step next time if you want to use that printer again.
To change the number of copies, tap the plus (+) or minus (-) button. If the document has more than one page, you can limit which pages print by tapping Range and selecting the start and end page numbers. When you're done, tap on Print.
Your document will begin printing. While that is in progress, you can double-tap the Home button and then tap the Print Center icon to view and manage your print jobs; Print Center disappears when printing is done.
Printing without AirPrint
AirPrint is certainly easy to use, but it may not meet all of your needs. Some apps, and some printers, don't support it. Plus, AirPrint offers no control over things like paper size or print quality, and it doesn't work when your selected printer is not on your local network. For these reasons and more, you may want a different sort of printing solution. Of the many other third-party printing apps, I personally prefer these three:
Avatron Software's Air Sharing HD ($10): This multitalented file-transfer app can print directly to any shared printer on your local network (with or without AirPrint), and gives you access to all your printer's standard options.
Microtech's ePrint ($3): Like Air Sharing HD, ePrint can directly access printers on your local network. Among the many things it lets you print are documents transferred from other iOS apps, Web pages, data from the Calendar and Contacts apps, and the contents of the Clipboard.
EuroSmartz's PrintCentral for iPad ($9): One of several iOS printing apps from EuroSmartz, PrintCentral communicates directly with Wi-Fi and AirPrint-compatible printers, but you can also install a small helper application on your Mac called WePrint that lets it work with virtually any printer. WePrint even lets your iPad print remotely by using an email account, iDisk, or WebDAV server as a channel for print jobs.
Senior contributor Joe Kissell is the senior editor of TidBits and the author of the e-book Take Control of Working with Your iPad, Second Edition (TidBITS Publishing, 2011).