I have 4, when I worked (Now retired, I'm 66) used to commute in city, rushed to get to work,in traffic, felt safer with it on.
Youtube has some good videos on helmets. and some online suppliers have clips, like Jensen & Universal. Bought my latest Bell, at REI, and it has an adjustable knob, to tighten fit. I like one that has a visor, and have added my own visors to some skateboard & snowboard helmets. Bike swap meets have some for $20, never like to pay to much.