Haha, I just happen to have a lot of clothes like that *-*
My internet's freaking out right now, so this is all from my head and probably not too reliable. Take it as you will xD
A lot of stores that sell EGA, punk, and even lolita have some boystyle mixed in. Some good places to browse are Black Peace Now, Fan+Friend, Alice and the Pirates, and h.Naoto. I have a few pictures, but I don't know when I'll get to upload them :c
When you're doing boystyles, you need to be careful to differentiate it from just looking like a well-dressed guy. For example, you don't want to be wearing a suit, tie and slacks.
Top: Tailcoats are amazing. Try not to use a dress shirt, but instead a long-collared or ruffly blouse. A blouse alone can, but usually doesn't, look good, so find a vest or a good suit-like top. (If I had to describe those, I'd say they're sort of... angular? Boystyle tops usually have tails in the back and/or front, and a collar like a suit.)
Bottom: Awhellwhatarethosecalled. For kodona (young/boyish styles) Pants that are a little poofy and cut off under, or above the knee look good. I forget what they're called (knickers? lol idk) but they're based on a style of pants that boys wore that are mid-calf with a drawstring at the bottom rim, and when the boys got older they worked like shorts. When you wear these, be sure to have socks that cover your whole exposed leg. Just like lolita, you don't show a lot of skin *n*!!
I also see a lot of people wear patterned pants (plaid, for example) that use a pattern from somewhere else in the outfit. )Not sure how in style this still is, since they look like pajamas to me.( Aristocratic styles usually have long bell-bottom pants.
Since the pants are usually pretty plain, you want to balance the outfit by wearing a top with long tails, or have accessories on the lower-body as well, like patches/patterns on the pants, chains, a "skirt" or buttflap, boots, buttons (not pins) or patterned socks (which I never think look good but w/e)
Accessories: Never wear a tie. I see it done, but it looks too modern... You could tie a tie the way you would a ribbon, which looks a lot more geared to the style. You should, however use a cravat/jabot (I forget which was which haaa), or a small ribbon, possibly with a necklace or crest over it. You pretty much always want something on your collar. Punk and gothic elements are often seen in boystyle, like chains, crosses, etc. You can also wear a brooch, rings, etc.
Dressy gloves look neat, but avoid shiny ones ono
A hat completes the outfit. Just be careful not to use one too girly. Don't let it look too plain, though. Get a patterned hat or add accessories to it, like feathers, flowers, chains/pendants, etc. Accessories are usually silver, gold, black, or whatever the accent color in your outfit is. You don't want it too clashy and overpowering unless it's for a single piece (black/red doesn't look that great ._. Dark red, or a red plaid can.)
Shoes: Again, try not to wear something too girly. You want something square-ish and clunky instead of pointed or round. Boots can work, too. If you want height, use platforms. Heels can work, especially in aristocratic styles where the pants can hide the heel, but you want to go for wide heels, which can be harder to find. I personally like wearing creepers |3
Boystyle is mostly done in white, and in dark tones. However, I really want to make a "sweet" style outfit, soon as I can think of something ._.
And don't worry about following all of this. Since it isn't done as often, it's a lot less strict and more experimental. Just play around with that, using those as some general guidelines.
