to help prevent tearing...
perineal massage
water birth - so the perineum is supported
squatting and all fours positions can help too
second time you will hopefully feel more in control, and more able to work with your body...there is no reason you will tear again, and if oyu do, that it will be bad....
i had first baby be emergecny c.s and second was a VBAC, with intact perineum, a small labial graze that needed a stitch or two.....no big deal !!
wondering if the diarmorphine made you a bit sleepy or out of it last time, might be better to try without it this time, use gas and air and water, so when you are pushing you are 'there' and able to push / pant / blow as needed!
also, you can prepare for afterwards...
arnica is great for bruising, and good for after a c.s or vaginal birth...salt baths good for healing, tea tree oil , i found that a pair of big granny pants and a thick maternity pad seemed to help support the whole fanjo area after birth which made me more comfortable
also, warm water poured over your bits when you wee or weeing just before you get out of the bath can help....