How do I share the gospel?

I had the opportunity, just the other day, to dust off my evangelistic skills. I seldom have reason to share the Gospel these days, which may indicate a certain glaring void in my Christianity.

Any one familiar with the bible understands that spreading the message of Jesus Christ is an important part of what Christians ought to do, but it's hard to know the best way to go about it.

Lots of books have been devoted to a variety of systematic strategies to introduce the uninitiated to the fundamentals of Salvation. You have 4 Steps, the Wordless Book, and so called "friendship evangelism." There's even some very popular, if inaccurate, terminology designed to streamline a sort of sales bid inviting folks into the comforting assurance of Eternal Peace. Every one of the techniques that I am familiar with seems to be lacking something. One of my main complaints is that they all make it sound like Jesus wants to "live in your heart" in a very warm, and nonintrusive, symbiotic existential way. It's often silly, and usually quite useless for effecting real change in a person's life.

People aren't changed. That's really the thing.
I know too many "Christians" who are not the least bit bothered by sin. I know others who are way too enthusiastic about regulating sin in everyone else. I have talked to many who prayed at some point to be forgiven by Jesus, but they have never been effectually transformed by the Power of this Creator God.

What is it to be a Christian?
How do you explain to someone how to become one?
Why would anyone want to?

I believe that the process is best understood with a thorough understanding of both Old Testament and New, but it can really be  presented with very little understanding at all. The bottom line looks like this:
You and I are filthy with sin.
God, by His very Nature, can only accept absolute perfection.
So, we are unacceptable.
Jesus is God and therefore He is Absolute Perfection.
Something astonishing happened at the Cross, whereby Jesus literally traded places with you and me so as to receive the just judgment of God upon Himself, thereby satisfying the penalty of sin.
This "trading of places" is the heart of Salvation.
I give all that I am (wickedness, foibles, talents, and time) to God, for all eternity, beginning now.
He gives all that Jesus is (attributed perfection, freedom, abundant life, absolute acceptance) to me, for all eternity, beginning now.
Making the trade is Salvation.
Making the trade is what it is to become a Christian.

Here is how this differs from the concept of Christianity that I often see around me: I am now not my own, but am rather bought with a mind-blowing price. I get to be free and forgiven, which is radical when you look at how completely undeserving I am. This emphasizes how total the exchange is, and that is what is often lacking in the Fire insurance sort of Christianity.
We stress the Grace, which is undeniable, but lopsided. The proof is in the pudding, as it were. If you are not changed, then you are not saved.
I understand that we are saved by a gift of grace, and that there is nothing to be done to earn it. However, there seems to be a misunderstanding that one can be given the generous gift, and then proceed as before. This is not so.
If we bet on a one-sided trade, we are fooling ourselves. If I get all that He is, He must also get all that I am,
Or no trade was made at all.