First ... porn is nowhere near representative. A lot of porn looks terribly uncomfortable for the recipient, IMHO.
5.3" circumference?! Sounds ambitious! You should familiarize yourself with smaller ones first. Personally, I wouldn't go anywhere near that size. This one is a decent starter: http://www.amazon.com/Golden-Triangle-Jelly-Bender-Lavender/dp/B00DY084DI
Lube.. if you think you've used enough, use more!
And, go slowwwwwwwwwwww.