While I gave it up years ago after I finally got caught and went to jail for 45 days (I was already on probation) and do not condone it, I will give you some tips so you don't get caught especially since your just doing it to get shyt you actually need. I was doing it at Nordstroms and Nemian Marcus for a couple years and got that shyt down to a science, even did it at clothing stores I worked at while on my shift.
Wear relatively baggy jeans and a coat/hoodie that covers your crotch and is a little baggy. Grab a couple things like jeans and a hoodie that will cover things up. Place them down over what your thinking about jacking, walk away a few steps like your looking at something else, then go back and pick up your stuff on secretly pick up what your gonna jack that was under it. If your doing jeans then unfold the pair ontop of the ones your gonna jack and when you fold em back up fold them over the pair underneath it. This makes it seem to the security cameras and/or employees like your bringing into the dressing room just the things on top that you have shown.
Once in the dressing room you have to take the sensors off, if they have them. They will always be placed on the stitching, take the senor from both sides and pull it down hard enough to rip just one of the stichtes, this will provide a hole big enough to slip the senor through and will create a very tiny hole you can sew later. Place the senor in a pocket of an item your not gonna take. Fold up the item(s) your gonna take and place it in your crotch so that most of the item is hanging behind your nuts but get a thinned out part of it it put up by your waist/belly button and use your belt to hold it in place. If you do it right there will be no noticeable buldge, trust me I once bought something at the register with a $400 Marc Jacobs hoodie in my pants, but just incase have your hoodie/jacket over your crotch to conceal any possible buldge.
It is best to come out of the dressing room with the item your brought in for all to see and put them back, but if your nervous leave them in there, come out of the dressing room acting like your on your phone and talk like your in a hurry and quickly walk out to your car which is parked as close as possible, be friendly and smile to any employees if they look at you.
I did it because I was against the establishment and big business for charging so much fukking money for clothes, and if I can help out a struggling man than I got no problem with you fukking over big corporations