Step one: Don't actually touch the purse. The purse is not for real touching.
Step one and a half: This is important before we continue. Ignore the haters. People will try and bring you down about your purse holding, but don't let them.
Step two: Do not get your greasy, gross, disgusting fingers on the bag. That's kind of similar to step one, but step two reiterates that you should definitely not touch the purse at all.
Step three: Position the purse onto your arm (maybe with help from someone else, since as I said in the first two steps, you shouldn't be touching the bag).
Step four: The purse should rest somewhere between your wrist and elbow.
Step five: Make sure if the purse is near your elbow that it doesn't go PAST your elbow, because that is wrong and will look dumb.
Step six: Find a good spot on your forearm where the purse will sit comfortably.
Step seven: Make sure once the purse is resting, it stays resting and does not move.
Step eight: Hold onto doors as you walk down steps because since the purse is balancing on its own, your body will have to bear the rest of the weight.
Step nine: Only touch the purse in EXTREME cases, such as this one where it seems like the purse might slip and fall off your arm. Clearly you do not want that to happen because then your purse will be on the floor.
Step ten: Walk with confidence. Pretend like the purse isn't even there. It's just an extension of your body at this point, like a third arm or a tail.
Step eleven: On occasion it's OK to turn your wrist down and let the purse sway. This is normal behavior and can even put a little pep in your step.
Step twelve: Match your purse to your outfit and continue holding as you've done before. You've got this.
Step thirteen: SMILE! You've been holding a purse like a pro for a while now. You should be proud!