Tips for learning finesse and improving? Options

[retep]

So, I want to get better at tetris and have been learning some new things to do so. About 2 weeks ago I was getting sprint times of about 1:45 on average (on FB sprint), with a best of like 1:35 ish. I decided to finally learn a second rotate and a few days ago feel I got it down pretty well and am now averaging about 1:35 with a best of 1:24.xy. I figured next it would probably be a good idea to learn finesse as everyone seems to mention it. Along with this I got the mod from: http://harddrop.com/forums/index.php?showtopic=4162
and I highly recommend it. It has been immensely helpful thus far.

Anyway, after downloading that I did a few test runs and had a sprint time of about 1:35, as I mentioned and about 70 finesse faults on average. After looking at the wiki and using the mod I started figuring out ideal placements for the pieces. After about 3 hours (over the last 2 days) working at it I now seem to make about 10-15 faults on average but my sprint times are like 2:00-2:20 as I spend more time thinking about the placement of each piece as opposed to before where I knew exactly how to place each piece, but it was sub-optimal. I seem to have most of it down but am still struggling a bit with the S and Z pieces as I got into the bad habit of always rotating S to the left and Z to the right to simplify things while learning the other rotate. There are also some odd cases that I sometimes mess up (I pieces to 3rd column from either side).

Anyway I was just wondering if you think I am taking the right approach in trying to learn all the finesse movements at once and taking my time during sprints trying to limit my finesse mistakes and slowly build up my speed? Or should I focus just on like S then Z or try to continue going at near full speed but try slowly incorporating as much finesse into it as possible, slowly decreasing my faults as opposed to my sprint times?

Any other advice or tips you have? Perhaps some common mistakes you know people or you yourself made when you were around my sprint times that helped you improve?