i learned em to fakie first and it helped me with straight pop outs. start out by doing the same shit with your legs as you would with the crook to fakie but try to keep your upper half straight. as soon as you feel that the truck has left the ledge straighten out as if you were doing a noseslide. if you don't understand what i mean, try looking at it this way: let's say that when you're doing a k grind your board is turned 45 degrees frontside, away from the ledge. when trying to pop out. you keep on rotating frontside like you would with a crook to fakie, but as soon as you feel that you're starting to noseslide (around 55-60 degrees frontside) you twist backside to land parallel to the ledge, rolling away straight. it's kinda hard to explain but i hope that it's going to help, that's how i learned these so it might work for you as well.