(This is perennially useful info, so now we are sticky. ^^)
Crossplay chest binding methods recap from previous threads, as I recall:
1) ACE bandages (I strongly recommend 6" wide actual ACE brand; store brands are not as solid - this is my original method.)
2) Tight sport bras
3) Compression shirt: http://www.underworks.com/997.html
(works quite nicely, but will show under anything skimpier than a muscle shirt - I used acid dyes to make mine skin-colored)
4) Combination of the above
5) "Waist-trimmer" girdle thing pulled up over the chest - I wear mine backwards to eliminate the vertical center line
6) Lumbar support belt / back brace (for women with larger chests)
7) Tied / pinned cloth wrap or narrow obi
8) Tape (preferably something designed for skin!)
I trial-ran the Sports Tape method (for a binding-less chest front - you can show REAL SKIN all the way down!) at Anime Expo.
a) I used Johnson&Johnson brand sports tape. Unlike duct tape and other such, it's designed for use on skin - typically to add stability to weak wrists, forearms, ankles, shins, fingers & toes. Duct tape and others are also well known to remove lots of skin along with the tape itself, so I had NO desire to even attempt those.
b) I tried this method in order to achieve the "natural guy-chest look" in a low-cut tank-top shirt with only skin showing, not a bandage. Method of application: run one 5-6" strip vertically up the front of each of your "assets" - this will keep you "decent" if your shirt slips, holds you up higher, and provides an anchor strip for the rest. Then run long strips horizontally from one to the other around behind your back, making sure to tape down any bulges showing on the side.
c) I have my doubts about this method working for anyone above a B cup, but I got TOTALLY flat with it. Whoa. *blink*
d) Since sports tape is a nice absorbant cloth tape, liquid foundation worked real well to color the parts of the tape that showed through the loose tank-top arm holes.
e) I did this on two successive days. Each time I started with squeaky-clean showered skin, and the tape did NOT pop off at all the whole day long, even after lots of running around and posing and sweating through the masquerade and evening dances. In addition, it was pretty comfortable. I think it constricted my breathing less than an ACE bandage (and not enough to trouble me.)
f) Caveat: The first day I took it off rather too enthusiastically (I was in a hurry and tired), and since the skin on the chest is not nearly as tough as the skin on one's extremities (or one's back, apparently), I actually did lose about 1cm sq. of top-layer skin in one spot. >.< I was much more careful the second day (didn't retape that spot either, obviously), but I did lose a couple more very small pieces (2-3mm sq., times 2) in nearby places. (NOTE: See EDIT 2 below for my latest theory on skin loss via this method - it's actually due to blisters forming!! Not tape glue being too strong.)
g) Result: I was happy with the effect while wearing it. I might consider trying this again, but I may not get any more chances because my husband was super-freakin' pissed at "the damage". (He already hates it when I bind. Grrr. It's not like I do it except for crossplay a couple days a year! I also cosplay GIRLS, for heaven's sake!! In fact, I typically cosplay more girls than guys!) Oh well. I suppose I can continue to Photoshop ACE out of my photos...
Post #62 in this thread describes this tape method in even more TMI detail!!
Post #4 and post #44 have my attachment pics of the result; there's another one somewhere in this thread that Mochihead posted from Cutekawaii's pics too...
I find itchiness under the tape usually means a blister is going to happen. Blisters = loss of 1 layer of skin on the spot where the blister is, so I try to pay attention to that. I do not like to lose skin.
SPORTS TAPE METHOD as used for FULLY OPEN FRONT SHIRT: http://images.cosplay.com/showphoto.php?photo=229474
Professional medical-quality adhesive remover is my best (crossplay taping) friend now. Opti-Sol brand, BTW: http://www.mhrw.com/c_solvents.html