Never own a saw with teeth smaller than you can see to sharpen. (Those saws are for detail inlays, musical instruments and dental work.)
If you're sweating (even in Brazil) while sawing - the teeth may no longer be sharp.
Lubricate the saw "above" the tooth line with wax, oil or tallow.
The "set" or sideways projection of saw teeth is important:
too little and the saw will bind, too much and it won't cut straight.