To be honest the best thing to do is stop trying.
I haven't got my knee down yet - no leathers with sliders - but I've been over far enough that I've had to lift my knee to keep it off the ground
There's a few factors - getting comfortable with cornering, leaning AND hanging off on YOUR bike. That is, you've got to get familiar with all 4.
As you go faster you'll find the need to lean more, then you'll get used to leaning more, then before you know it you'll be scraping your knee.
If you can get out to the track I'd recommend it - a safer place to practice than the road. But if the road is all you have just take you're time - you don't want to screw it up
hth
ty
If you have no fear, you're not going fast enough.
Never argue with an idiot. He'll drag you down to his level, then beat you with experience.