How do you pray for forgiveness?

Pretty early in life, I was taught to pray something like this:

"Father, forgive me of my sins."

As I got a little older, the Lord's prayer had more of an influence on my prayer life and this part of my prayers turned into:

"Father, forgive me of my sins as I forgive those who sin against me."

As I matured in my faith, I began to realize there were “sins of ommission” which were just as offensive to God as the “sins of commission.” Therefore, I found myself praying along the lines of:

"Father, forgive me of my sins as I forgive others... both those sins where I have done something wrong... and those times where You wanted me to do something and I did not."

Lately, however, I have thought a lot about Christ's one-time payment for all our sins. Surely Christ was aware that He was substituting Himself for me even though I wasn’t even born yet. That means He was offering himself as a living sacrifice for sins not committed yet. It seems that the forgiveness is on-going and once we are saved we should be thanking God for forgiveness that He has already granted. As a result, I wonder if a believer should pray something more like this:

"Father, thank You for forgiving me of my many sins as I forgive others... both those sins where I have done wrong and those when I failed to act on faith when You needed me to do something. I thank You also for continuing to forgive me both now and in the future for sins I will certainly commit in my future weakness and lack of faith.”

Maybe I'm crazy. Opinions are appreciated and encouraged.