Here's a reddit post from a checkout clerk https://www.reddit.com/r/IllegalLifeProTips/comments/gqwtcd/ilpt_how_to_shoplift_effectively_as_told_by_a/

Don’t wear loose clothing. It’s incredibly suspicious, especially in summer.

Don’t carry a bag. Also very suspicious. If you do happen to have a bag, ask if they want to check it, 9/10 they’ll let you go. In the event they don’t, they only really check the main pockets.

If you have any distinctive features (dyed hair, tattoos, etc.) cover them completely. If you can’t 100% cover them, leave them be, it’s less suspicious.

Actually buy something. It’s a dead giveaway if you’re leaving without buying anything.

If it’s a store with scanners at the exit, go through at the same time as someone else. Odds are, they’ll freak out, giving you time to bugger off.

Wear unremarkable clothes, jeans, plain shirts, etc. especially avoid logos and bright colours.

Only steal from large corporations. Not only is it far more ethical than ripping off a family-owned business, but the employees are less likely to be on the lookout.

If it’s a 24/7 Store, don’t shoplift at night. Come during peak hours, when we’re too busy serving to worry about shoplifters. Goes double if you’re a minor, unattended minors at night are super dodgy.

Only steal what you must, and don’t do it too often. The less you do it, the less likely you’ll slip up or get noticed.

Confidence is key. If you look shifty, you’ll get caught.

Here's a comment I liked too.

Be a normal person. (Bonus: be a gig shopper who is in a hurry) Wear a jacket in. Shop as normal Put a few things in kids seat. Get hot. Take off jacket and put it over things in kids seat. Continue shopping as normal. Pay for things in cart. Walk to car with bonus items under jacket. If caught, "omg how silly of me, forgot all about it." Be a normal person. Everyone laughs, no bonus today.