If we do manage to get her to keep her ears still and up, the prick is pretty easy. She's also learned shaking her head makes it very difficult for us to 'torture' her.
Assuming that you are right-handed: have the light to fall on to the kittie's head; sit behind your kitty who is also in a sitting position. I keep mine between my knees while I am leaning over her on the bed - my feet restrict her backward crawling but does not make her feel trapped in a bad way.
With your left hand hold Jumbo - Large- size ball of cotton against the inside of her ear with your left thumb and index finger flattening the ear against the cotton ball on the outside of the ear, the left middle fingers lays underneath the cotton ball giving it firm support; the outer edge of your left palm lightly rest on the kitty's forehead covering her eyes - very lightly, do not rest the entire weight of your palm on her head but block the view and hold your fingers firmly on the ear.
Have the lancet opened in advance in your right hand; the outer edge of your right palm lightly rests on the kitty's back head - this way her head is sort of surrounded by your palms minimizing the movement, and blocking the view. The head shake is still possible. The firmer, but not tighter, you keep both of your palms the less chance the shake has.
Aim at the "sweet" spot at an angle, do swift definitive poking movement and immediately after your got the blood bead throw the lancet away, pick up the meter with your right hand (strip is in in advance, of course), return your palm to the previous position with the outer edge of the right palm on the back of the head and dip the strip into the blood. If you do not get sufficient amount of blood to sample, hold the ear as you were, throw the lancet away and with your right hand make milking - moving the blood toward the pierce point, gently. You need very little blood for the Relion Prime.
I hold the strip in the blood until the reading is ready - a few sec on ReliOn Prime human meter. As soon as the reading is done, put the meter aside, grab 2 smaller cotton balls with your right hand and press against the poke site for a few second - one piece on the outside and another on the inside the ear. That'll stop bleeding and help the ear to heal. A small snack afterwards goes long way.
I hope this description helps and not confuses. I had to learn to do all of the poking on my own. It gets easier with practice. The ear also learns to bleed properly with time - and to heal, too.
Sorry for the length, I am not good at explaining but wanted to describe the method as best as possible. I promise - you will test in seconds in no time although I know you cannot believe it now.

Hope what I typed makes sense.
Best of luck to you and Martini (cute name)!