I was taught by the parent who raised me that you hold open doors for people, give up a seat for your elders, etc and that has always stuck with me. I hold the door open for people regardless of sex, age, etc, if I see an elderly person needing a seat I'm in I give it up, or regardless of age if the person is tired I'd do the same. I just feel it's common courtesy, maybe not so common anymore but still. Sometimes I get weird looks when I hold the door open for a cis male, a couple have told me to go in first very sternly it was quite odd. Usually though people either ignore it and go on through or smile/say thanks.