I haven't done this in a long time, well not seriously anyway, and a lot of this was done during the 20th century, so it may not be so up-to-date, but here is a guide I wrote and posted elsewhere, slightly revised:
Have a plan, know what you are going to get before you go in and do not deviate. I used to find the nearest meth dealer and offer my services. Some of them are car guys, and some of them need lithium batteries, and some of them just know a lot of people. I would get lists of stuff and fill them like santa, for 20% of retail price. Auto parts stores, hardware stores, department stores, the best places didn't have source tags. But I did most of my work during the 1990's before that technology was widespread, and I never got big-ticket items so never used the wierd detaggers and tools you kids use nowadays.
First of all, never get so desperate that you can't walk away if something doesn't feel right. You can always go one town over and probably find an identical store. but you can't take it back if you get caught.
Wear something unobtrusive, in neutral light blues or greys. Do not wear anything 'trendy'. Do not wear 'tennis shoes' or 'sneakers' or whatever the fuck they call them. Do not wear combat boots or any sort of boots. If you do not have a decent pair of shoes, spend twenty bucks and get some cheap ass ones that fit from pay-less, some black or brown dress shoes or 'loafer' type shoes. Leave your identification at home, and carry any money you have. All of it. I will get into why later.
To be successful, you will need to be somewhat of an actor. Not a 'face' actor, working with emotions, and expressions...you will be a 'body' actor, and you will have two 'modes' or 'characters'....the 'normal shopper' and 'the lifter'...the normal shopper does most of the work and the lifter only comes out for a second, when the moment is right. After the lifter does its work, the normal shopper takes over, this time with a 'I left my money in my car' role as you make your way out of the store.
As part of your 'body actor' training, get into the habit of 'using your peripherals' instead of turning your head...don't have a 'head on a swivel' response, it looks guilty and is a body language 'tell'. 'Normal shoppers' don't look around exaggeratedly before shoving a fucking steak into their jacket. I have a friend who's 'style' is exactly like that, and he is visually striking as well. He is 6'2" and resembles a dick tracy thug, with a face like a bad apple. Usually drunk, he staggers through the store like a Frankenstein's monster clad in a carhart. I suspect that any success he has is primarily due to the store employees fear of confronting him than anything else.
When parking, it is best to park in another store's parking lot, or somewhere off the property. Don't be an idiot and park in a place that will call attention to your vehicle, or someplace that might get you a parking ticket or something. If you are lazy or can't find anywhere else to park, then make sure you leave the car unlocked, keys in the car, easily retrievable but not in the ignition. This is so, if you get caught, the cops won't go look for your car and search it when they search you and find your keys.
Enter the store doing the 'normal shopper' thing. Don't hurry, take your time. Get a cart. Always, get a cart. The action of pushing the cart around and putting items into it just reinforces the 'normal shopper' act.
Follow the natural arc of the store, going right from the entrance and around part of the outside perimeter before going anywhere else. If in doubt, just follow what the other shoppers are doing. Pick up a few items on the way, larger items like bread or a bunch of bright bananas. Part of shoplifting is misdirection...like the times I used to get dozens of tins of poppy seeds at once. Small, two oz. tins. It would look suspicious walking around with a cart full of poppy seed tins, so I would use bags of chips or bright colored items to conceal or draw the eye away from them, to call less attention to myself. Once you find the item you are after, get it and put it into the cart for later concealment.
All this time, even when acquiring the item, keep up the 'normal shopper' act. Since you haven't yet done anything wrong, you still technically are a 'normal shopper'. Once you find your targeted item, if you are acquiring multiple items at once, get as many as you can with one hand rather than using two hands to get multiple items from off the shelf. It just makes a different body language profile and looks out of place in a store setting to be grabbing multiple items from store shelves with both hands.
Once the items are in the cart, your next step is to find an empty aisle. I suggest the 'chip' aisle if you can, or any 'freezer' aisles that are not around the outside wall of the store where the dairy is kept (they can see through the windows of the dairy section).
find an aisle with no one in it, and, with the least amount of movement possible, conceal the item while using natural types of movements, like disguising it as scratching an itch or putting away a cell phone.
I would do it while wheeling the cart with one hand, walking, concealing the item with the other. No one thinks anything of a guy pushing a cart down an aisle. It is much different than the usual 'open coat, shove item down front of pants, close coat' exaggerated movement of most shoplifters.
Nothing wrong with shoving an item down the front of your pants, mind you, but you can do it smoothly, without exaggerated movements. Another good concealment place is under your arm, as long as you don't drop the item (Who threw that at me?) and can keep your shoulders loose and normal looking. As stupid as it sounds, practicing this stuff at home might help.
large potted plants or items like cheap coffeemakers are good places to conceal smaller, expensive items like lithium batteries or drill bits/dremel parts...just stick them in the soil or open the box and put them inside, then close it again. Just make sure to find the kind of box that opens easily without being taped. You can always return the plant or boxed item later.
Store credit can be useful, and sometimes I would steal expensive items just to return it. In wintertime, a couple of bottles of expensive olive oil, or cake decorating items, make plausible returns...'My wife sent me to get this stuff but I got the wrong kind and now she is pissed'...most times the store employees don't care, but it is always good to have a story. I would get items, walk to my car, change my hat and shirt, and go right fucking back in there and return them. Never had any problems.
I wouldn't worry about any cameras, as once you conceal the item, you should just leave. If you don't hang around, they won't have enough time to mobilize against you. Oftentimes, once I concealed my item, I would abandon the cart and leave the store. You know, because I left my wallet in my car. Or because I forgot my money at home. Or just because I changed my mind. Normal shoppers do that sometimes. You are just a normal shopper, remember?
While leaving the store, you can be doing something like looking down at your cellphone with a concerned look on your face, or holding and paying attention to, and possibly counting money, sort of like 'I only brought three dollars in with me? I can't believe it!' or something. It really doesn't matter, its just a prop, something to keep you from looking less like a guilty shoplifter leaving the store, and more like a busy, harried, confused, dorky, normal shopper.
Some people say that you should buy something when leaving, to blend in better or allay suspicion. I did once in a great while, but only because I was so good that I knew there was no goddamn way anyone was going to catch me (I have been wrong before, but I always got away). I would say don't do it, it won't help you at best, and will allow them time to find and detain you at worst
If you do end up buying something, and you have an item down your front, or bulging in a pocket, you can sort of hold the bag that you just purchased in between you and any onlookers. Be subtle about it, though...don't awkwardly hold it over your front, and bring attention to yourself.
Once you leave the store, walk quickly to the general vicinity of where you parked, but do not go directly to your car. Walk past it, and keep going for a fair bit, then turn around and check if you are being followed before 'sheepishly' going back to the car you 'lost' and were so 'busy' and 'harried' that you just 'walked right past it'in the parking lot. This is to avoid leading store employees or loss prevention to your car, which will be searched and possibly towed if the police get involved.
As soon as you get in the car, even if not 'chased', hit the 'door lock'. This has saved my ass before, seriously. I have had store employees literally open my doors and try to drag me out of the car.
This article is written under the assumption that the reader does not plan to submit if confronted by store employees. The author of this article does not advocate any sort of violence or resistance, but does hope that you get away.
If caught, realize that this was always a possibility, as you are indeed committing a crime by planning and carrying out any sort of retail larceny. In some jurisdictions, planning to shoplift is a felony. If you are carrying money with you, then you can claim that the theft was 'spur of the moment', and will get in less trouble.