I used to have a Tri Top from underworks. It worked well, but cut into my skin alot, make me bleed, and wore out.
(I'm really a 34c/d, but due to binding for years my breast tissue is broken down) I came up with an interesting method to bind. One day, being homeless, and desperate to hide my chest, I threw on two sports bras, and grabbed a belt, and put the belt around my chest as tight as it would go. I'm using one of those belts where there's two metal things that you put it through, not a normal belt, but I'm sure a normal belt would work too. The material is stiffer so it works well, suprisingly. It's the flattest I've seen my chest in ages. I put it around the middle of my breasts, so the top part looks like pecs, and what sticks out underneath isn't noticable if I wear a not too tight shirt. Plus this is winter so I wear underarmor, and a beater underneath my clothes. I hide the buckle under my arms. I've been hit on by gay men at the gay bar so I guess I"m doing something right!
My ftm drag buddy uses black tape on his chest everyday...idk how he does it >.< When I do use tape, I use duct tape, but over a beater so it's not on my skin. I have asthma, and the belt method allows for very good breathing, IMO.