Looser tshirts are a good start. The more air circulation you get under there, the less likely the under-arm condensation is going to cause havoc.
Know your options. Sweat resistant clothing does exist, some are even designed to prevent smells, so they're a safe bet for under winter clothing options.
Those who'd rather take the gamble will find wearing natural fibres on warmer days. The more natural the texture, the more your skin can breathe and you can get on with your day.
Anti-sweat accessories are a last but effective resort. Acting as 'sweat shields' the clothing liners stick to your skin and keep your clothing and dignity out of mischief.
Feet are where most of your sweat glands are hanging out. Choosing the right footwear is not only a matter of presentation, but requires thought to hoof precipitation.
Avoid synthetic and cheaply produced materials, as well as think about swapping the canvas for leather. These simple choices will help with air circulation which you can take a step further with tailored insoles to inhale any sketchy smells.