There are some things you can do to aid the sweating situation.
I roll in blazers often. And I used to even wear my denim jacket in the notorious Taiwanese summer (Hot as BALLS).
I typically do a few of these following things. (Note: These tips may not be advisable for everyone, and could depend on your specific style, but I'll share just in case)
Douse yourself in aftershave
Literally grab the bottle and spray it on your neck about eight times. Smelling bad is NOT an option.
This
absolutely goes against the general consensus that you should be subtle with your smell, I know.
But a) Smelling of aftershave > Smelling like shit
b) I've only ever had good things said about my smell. Girls will often text me randomly asking what my aftershave is.
and c) I often think 'smell-based attraction' is more psychological than literal. If a girl smells aftershave, it'll trigger something in her brain and make you seem more attractive. My aftershave cost $5. I bought it from a Taiwanese pharmacy.
You can always douse yourself in roll-on deodorant if you want a 'less overbearing' smell. Like, roll it all over your body. (If I wear my cravat, I douse that in aftershave/deodorant as the smell stays on that for longer).
This will prevent you from smelling like shit. After a while, you'll be able to gauge how much to put on.
Roll your blazer/shirt sleeves up
Cools you down a little and feels MUCH more comfortable in the hot weather. (Also can help you look more masculine, less wooden and more 'in control' of the garment, as stated earlier)
Drink lots of water/Coconut water/Sports Drink
My 'Captain Obvious' entry.
But, this really does cool your core temperature down and can prevent you from sweating.
Coconut water, Pocari Sweat and Sports drinks can really help to prevent sweating. I always drink one of these before going into a club. Don't underestimate their power. (Luckily in Bangkok/Taipei there's always a 7-11 handy.)
Roll your trousers up
The hipster entry, and probably something most guys won't want to do.
I touched on this earlier, so I apologise if I'm repeating myself.
If done correctly, I think it can look good. In Asia, this can help you look like more of a trendsetter than a follower in my opinion. (Plus, it avoids the 'I've just come from my bank job look'. I do this when I don't wear my converse.)
If you do this without socks, then it allows your feet and legs to breathe more. My friend has a huge problem with sweaty feet, so this could help him.
Just don't do it like a hipster:
Don't be afraid to try a few of these things. It will really make you seem like you know what you're doing with fashion. Most guys won't do it because 'It's gay/hipster', but if it attracts Asian girls than I'm all for being a hipster.
If you're not wearing a blazer, then I think you have to add an 'interesting' item in order to make yourself stand out. Everyone else in the club will have a shirt on. So, perhaps add some shirt suspenders ('Done up' to look sexy, or 'hanging down' to look 'rocky'), or a dark cravat, or roll your trousers up. Choose ONE of these things only. It's dressing well, NOT pea-cocking :-P.
But yeah, really, it's best to avoid a blazer in hot countries. A clean, white shirt is excellent advice in my opinion. White is a sexy colour, you'll stand out.
If you're skinny like me, try and find a 'Zara'. They have some excellent tight-fitting shirts. They hug your body. The shirt MUST fit.
And try to get something that doesn't make you look like you're wearing a school uniform shirt. Avoid buying a shirt from Uniqlo or something, they'll be low-quality and tacky.
In Asia, there are plenty of shirts that have a slightly 'shiny' texture. They feel a bit smoother than normal shirts, and they'll be slightly thicker and won't show up your nipples. These are the good quality ones usually.
It's also good to find a shirt that has SOMETHING on it which makes it a little bit different to that white shirt, with white buttons that you wore to school. Maybe it has an extremely subtle logo (like a tiny, white Lacoste logo), or buttons in a contrasting colour.
I.e look at this:
The black buttons prevent it from looking like the one you used to play football in at break-time before Geography class.
Also, something that I haven't seen mentioned on this forum before:
Foundation (for Spots)
This is a little bit off-topic, but:
I'm still young and I get the occasional spot/blemish on my face. (And sometimes I cut myself shaving.)
Get some girl's foundation and gently dab it on the spot. It makes it disappear and looks 1000 times better than having a juicy red blob on your face. No idea why more guys don't do this. It means you can go out without feeling self-conscious.
(Disclaimer: I am NOT telling people to wear foundation on their face :-P, just good for covering up spots and blemishes).