Two things that have improved my riding
1. Look ahead
2. Pick a line and let go of the brakes. (but be aware when you will need to brake!)
if you do number 1, its easier to do number 2
You might see a bit that looks really sketchy, but as a matter of fact its a bumpy but straight route to the next corner (looking ahead will tell you this). Trust your bike will make it and it probably will
As for corners do all your braking early, relax and look where you want your bike to end up. As you improve, you can brake later and a bit less before going into the corner. I find a deliberate head movement that looks as far out of the corner as possible helps the bike point where it needs to go.