get a good noseslide dialed in. knowing bs 5050 helps.
I bend my knees more, put my foot further back on the board than a noseslide to prep.
Unlike the noseslide, you can't just bash it on there and expect it to slide. to lock in is to get your lead foot's heel right above the angle iron. The art lies in getting your truck to lay perfectly along the grinding surface, in the crook position, no foot adjusting mid-slide, (the noseslide allows this, crooks dont.)
for exiting the grind, i found the best thing to do is learn the easy 180 out first, it's like a noseslide to fakie, and once you get used to that feeling of being centered over your bent truck & sliding to fakie, you will get bored and learn it to forward by default. Or you can pretzel whip it and get a cheap 270 out, which impresses people who aren't on Slap.