I buy my my 3m Transpore in bulk (12 rolls in a box) from Amazon and have had great luck with it. I use a variety of wig/lav elements taped to the cheek, and single ear ear-set style. It is important to note that the tape has to go on dry skin to start. a little toweling/ and Rubbing alcohol to
clear of skin oils/sweat before placing the mic and tape is important. When time permits I mic actors before they have gotten into what ever hell the costume designer has put them in (like 3 piece wool suit.)
Proper
strain relief on the cable is also important. Tape cheek/or front of ear (depending on mic) Tape back of ear ( cheek/front of ear, behind ear are both places the muscles won't move the tape.) then if placing the mic on an actors right cheek, ask them to tiled there chin to the left and down stretch out the
wire and a little piece of tape on the back of the neck, just in
line with the shoulder horizon. (sometime if you have an actor with a large neck or neck folds and creases, ask them to tilt there head back and make a note of where the indents are, and don't place the neck tape where it will fall into a crease when the actor tilts his head up.
Pieces of tape that are to big will span across muscles in the
face/neck and back and actively work against the tape staying in place. I find small 1" by 1/2" to generally be a good size.
If all else fails, during rehearsal, I go the little
bit extra mile, and cut up small 1/4" by 3/4" pieces of double sided wig tape. and place them just under the locations I place the Transpore. I
lay the mic on top, then tape over the mic and the wig tape with the Transpore. (this process takes a little
bit more time once you get the hang of it, and another 5 minutes extra until you finger get used to dealing with the double sided wig/toupe tape.) I generally only need the double sided tape on the cheek/front of ear, and behind the ear in the instances.
Ask the actor to
roll there shoulders and turn the head far left, right, up, down, and ask them if they feel any tugging or pull on the
wire. If they do fix it right then and then. Generally I've found that when they feel pulling on the piece behind the ear, it's because the tape on the neck didn't leave enough slack.
Sometimes you'll still need to reapply during particularly intense shows with very active dancing or costume changes that may bump, or rub against the mic
wire.
I do many community theater, and semi-pro productions ranging from kids to adults and these are the tricks combined with other knowledge bases like these forums that have worked for me.
Nick