The way I lift clothes where a clerk counts the items and give you a number is simple and effective. I always take a shopping bag from the store and pick as many clothes, or near the limit allowed in one trip at the fitting room.
I look for a pair of pants that have very narrow ends where the legs come out and put one or two smaller and very light shirt inside of this baggy pants. All is done inside the bag so I dont even have to be at a very blind spot. I even go to a mirror and pretend to be checking the items on me before going to the fitting room, but I'm actually moving the shirts inside of the pants. With these two small and unnoticeable item inside of the pants, I fold the pants in my arm, place another 2 items above the pants letting in sit on my arm and approach the fitting room. I always make a little acting saying something like "oh my, did I get too many stuff, whats the limit"? Or sometime I drop some hangers with clothes on the floor to create some distraction and apologize saying "I'm so sorry, I made such a mess inside the bag, its all mixed together (this way I also prepare the clerk in case they find the hidden item inside of the pants).
So the clerk counts the items, and I usually show the ones I have in my arm one by one so they can count while I am handling it myself (sometime they pick it up from me and thats why its important to choose a big pair of pants that wont allow for the hidden items to fall from the leg holes, they gotta keep inside it).
They dont care about what items you are bringing in and wont remember which ones you gave back, they just care about the quantity. So after cleared, I go to the fitting room with 2 extra hidden items (I never get more than 2 at once when they count because supposedly they went inside the pants by accident!) so now I can remove the tags from the 2 items I am really interested in, WEAR them under my clothes, hide the tags in another item, inside a pocket that has a zipper, or if the tag is too big, I hide somewhere in the fitting room where it will take sometime to find. If the tag is re-attachable, I just re-tag it to another item. I leave the stall and hand back to the clerk the same amount of clothes as the number they gave me, and that's it! NEVER BEEN CAUGHT doing this.
I dont see people talking about this here, but I always check if the mirror is real of a two-way mirror, meaning someone or a camera could be watching behind it. Its illegal in most places to monitor fitting room, but ALWAYS PLAY SAFER THEN NECESSARY Check the link to see the tutorial on how to identify "fake" mirrors. If they are watching you illegally they probably wont bust you immediately, but they won't forget your face.
I dont carry tools designed only to hack tags as they will get you in deeper trouble if caught. I carry a swiss pocket knife, and I can remove most tags by force with it, I also prefer stores with those simples tags you can just rip off. I also roll some strong tape around my pocket knife (like those black ones used for electricity) so I can use it to stick tags behind the mirror or under the seats of the stalls. Never leave tags behind where they will be found immediately.
How to check for two-way mirrors: https://pbs.twimg.com/media/Csgko3yWIAEJXtP.jpg
Have a nice lifting!