I go to gigs (support acts are always one way of discovering new stuff) and then go to gigs that I would perhaps not ordinarily go to, keep my ears open, use Shazam, see what friends are listening to, look up genres and there'll be lists of bands within the genres. Listening to youtube videos of things I already like and there'll often be suggestions there or the person whose channel it is will have different stuff on it so I just check them out.