First of all, before reading this let me make it clear that these comments are not meant to point any fingers personally, but are general observations. With that in mind:
Starfish's observation about the old habit comment brought to mind one other point. I think one way you can distinguish religious people is how much of their practice is driven by conditioning. This behavior is very common and prevalent in all religions, even the ones that are non-theistic. The point is you really are not doing anything different regardless of the content or difference of belief, you're only doing what you're used to. This to me is about as DEAD as it gets, because anybody can do what they're used to doing, even non-religious people and animals do this.
The question itself of how to pray or whatever other how-to can be a type of conditioning, just another habit. It's this desire of wanting to KNOW, whereas when you get right down to it you can't REALLY know for sure - though you can just be yourself. Now I should note here that when I say be yourself I certainly don't mean go with your old habits, but at the same time don't try to re-condition yourself by forcing yourself into a certain way of behaving, because that is just an extension of your habit of wanting to know. This is true humility, not the phoney crap like sitting in the back of the hall or saying some humble sounding thing, as if words alone changes your attitude, (by the way, even if you really think you are unworthy and is human rubbish, that is still a self centered attitude - it's just that you have a low opinion of self) but simply and honestly acknowledging when you just don't know.
Look, if you pray then chances are you believe that God can read hearts, right? So what difference does it make what words you use? If it's all about being open and honest, then just be open and honest with yourself and let the words come out naturally. The real question is do you mean what you say? You can have the perfect little formula and include God's will, others, yourself all in Jesus name Amen but again that can just become a dead habit. You might as well be reading it out of a book at that point, because just because it is committed to memory it doesn't mean you mean any of it. "Let your yes mean yes and your no, no." - no?