I wear smart-looking work trousers and plain black shoes - both of which are a good compromise between comfort for working and image for impressing customers.
When I meet a customer for the first time, I'll be wearing a short-sleeved collared shirt with my logo on it, just like the Hydramaster ones if anyone's seen them.
To work in, a polo shirt in company colours with logo. I really can't work in a smart shirt, as said above you're forever tucking yourself in at the back and when I sweat I get a wet patch betwen my moobs
I think having a shave and a tidy haircutis more important than anything tbh.