And bras are SO wonderful. They're pretty much the only piece that, for men, has no real function, so we can concentrate on form 100%. In other words, they're the only item we can go nuts with sexiness, cuteness, colors, or whatever gets you your lingerie fix. I'm wearing a cute, lacy pink racerback bra that I actually got from walmart of all places. I wear 36B bras... Sockstuffing until my next paycheck, then I'll get breastforms for them. Naturally socks don't have the bounce that real breasts do. You REALLY SHOULD get a whole outfit to see how good you actually look. I like the two color look, and have a new blue/black set that I bought instore. Another advantage to shopping instore is you get a better idea of how stuff will look on you before you buy it.
My best advice, if you're serious, get a bra with a modestly sized (B or C) cup. I can't advise higher than a C because it looks too large, nor can I advise lower than a B for the opposite reason. If you're wearing them just for the look&feel, though, and don't plan on stuffing or getting breastforms, smallest cup is usually best.
There is no problem with a man who likes wearing women's clothing.
There is only a problem with the world around him that doesn't accept him.