I do not have a wireless printer. I've tried a couple of printing apps with varying amounts of success and frustration. Based on this thread, I tried Fingerprint. I am very impressed. Now, when I'm in an app and click print, boom, there's my printer, and my document prints perfectly. Couldn't be any more straight forward.
As an added plus, you can add your Dropbox account as a printer. A very fast/easy way to share a document with your pc. This is also a quick way to turn a web page into a PDF.
Fingerprint installs on your pc/Mac. There's nothing to install on the iPad. It comes with a full featured 6 day demo.