a Gaiter over your right trouser leg, and/or keeping the chain spotlessly clean ,

Paraffin-wax is a remove the chain and soak it in hot wax kind of situation, stove top, double boiler..
has many adherents..


a wipe down frequently to take off any dirt gathering on the outside plates may help.

+1 on the black pants, I have some Charity shop ones that I got altered to taper the legs
and added ankle zips to make a trouser swap quick and easy.

My Brompton folds the front wheel over the chain, so I never get close to it.
as I carry it on my right , the bikes left side.