i know how to do them but i just cant do them, what is the easiest way of doing them?

If you know how to do them but you just can't then obviously you just need to practice. It's basically just a matter of doing it enough that you find that sweet spot where it rings every single time.

My Guitars:
Fender Mustang.
Yamaha FG-413SL.
Most people choke up on the pick and hit the string with their thumb right after playing the note, but I find it easier to just rest my pink on the string and play the note and they come very easy. You usually get the best pinch harmonics when you hit the string around the neck pickup.
Current Gear:
Ibanez rg470
Peavey ValveKing 112
Blackheart little giant head
2 homemade 112 cabinets
Boss SD-1