Originally Posted by ChrisSlicks

I'd say for a start your tire pressures are too low for those tires. Shoot for around 37-38 front, 34-35 rear HOT. Measure/adjust the pressures after coming off track in the first session and you should be at a good place for the next session. Probably around 30 cold is a good starting place.

Try revising your driving technique a little, slow down the entry slightly and then squeezing on the power at or just before the apex and see if that helps.