Colette, pictured below, was my willing test
These next two photos show how the lav was attached to Colette. I'm using my jacket as a reference (no, I don't own any pink jackets for this simulation). The first photo shows the lav taped at the edge of the lapel. The trick that audio pros use for strain relief is to attach a piece of tape on the mic wire 1-2 inches after the mic, form two loops of the lav mic wire, and wrap the tape around the loops inside-out so the sticky side sticks to the fabric (as opposed to the loops of wire). The two loops held inside the tape form strain relief so your talent doesn't rip off the mic while shifting around or worse - break the lav mic wire. Not shown here for clarity sake is an extra step. You want to put another piece of tape over the strain relief just to make sure it sticks to the fabric otherwise the strain relief will quickly be dangling and useless.
The second photo shows me tugging on the loop. You can see that one of the loops is starting to close in as it should.
There are obviously more elaborate techniques out there, but this is a basic one any shooter should know. A google search will give you more information than you ever wanted to know.
For this demonstration I used medical tape to attach the lav to the jacket. In the interview I used gaffer's tape. For this configuration it doesn't really matter all that much. When you want to hide the mic under a shirt on some one's chest, the side of their cheek, or on their forehead under bangs/wig then medical tape is probably the better option. At least your talent will think so.