I am impressed with the fact that you are aware and asking.
James gave you great advice. When you work on yourself, you will feel how the inaccurate insertion hurts, where the proper insertion does not. First I worked on my legs, then my fingers. You must have good insertions to do those fingers - or OW!
You also want to look for dimpling of the skin around your insertion. The needle should glide into that follicle without moving the surrounding skin. You will develop a feel with your inserting hand where you recognize the moment that your insertion is going out of the follicle. That feeling is subtle - almost like pushing a fine needle through lightweight parchment paper.
My instructor was big on the three way stretch. (Some might call this "firming the skin".) Electrologists will argue about whether or not this technique is good, but I believe it can be very helpful. Your non-inserting hand will be two points of a triangle. The ring and little fingers of your inserting hand are filling out the triangle. The hair follicles being treated are in the middle of this triangle. Your first and middle finger, with the help of your thumb are inserting the needle into the follicle.
Are you working both needle and forceps in one hand? Are you treating one hair and epilating or treating several before epilating?
Even now, I try to evaluate my insertion skills to make sure that I am "ONE with the hair".
Best of luck to you.
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Barbara Greathouse, CPE
Kansas Licensed since 1980