I'm not very good at prayer.  I would bet that almost every Christian would say that and mention that they wish they did one of two things better: 1) prayed more frequently or 2) prayed more passionately.  

I have a hard time when I'm put on the spot; almost as though someone is handing me a mic and saying, "Alright now, Nick, talk to your Creator."  I mumbled like an idiot when I got the courage to talk to Britney Spears one night - it can be even worse sometimes when I pray and really picture who I'm talking to (see verse 12 below).  

That's why I like to pray with the Bible open.  They're God's words, use them!  It's like Obama's teleprompter x 3,000,000,000.  I especially like to pray with the Psalms because they're worship-directed and use language that exalts God and humbles men.