maybe try A and S keys on the left hand and I and J on the right one, this works great for me! I think it is VERY IMPORTANT to play spread, when i changed from 1 hand to spread i got like x10 times better in the same day (imagine how i sucked
haha).
Set a faster speed than x1, i set x1.4, x1.45 and x1.5 it depends on the song, just pick the one you feel more comfortable with, it's MUCH EASIER to get perfects on faster speeds, just test yourself how fast you can go, and practice when you get your limit stick to it for while, and then when you are good at it try to go a little faster, don't do it to fast or you just won't press any key ><, either to slow, you will make loads of good and averages.
I find it pretty obviously but listen carefully to the beat while pressing the keys... it will help a lot, i barely look at the keys.
when i try to master a song and it really frustrates me, I set autofail so every time I don't make a perfect or i miss (depending on my goal if it is a fc or AAA) i restart and try to get better at that part.
don't stick to much to a song, try to play all of them, I usually go random, or pick a high lvl and then a low one, for example in my case are usually the ones that are "hard" for my self for example i usually try to fc a lvl 9, 10 and then to AAA a lvl 4, 5.
another thing i do, is not to play hours and hours without stop, just play a while, then stop, and continue in another time or on the next day, i see it as a muscle, it needs to rest to grow :P (ya.. I love body building ¬¬), and then after a week you will see some good results
just giving some ideas about what I DO, i'm not good AT ALL at ffr, maybe it will help someone...
if you have any advices, questions, or anything you want to say reply me, i'd love it