So what form of exercise is in style nowadays?

when I was in high school, it was always "today is shoulder and arms. tomorrow is legs" so basically muscle targeting. Then it was all the push muscles one day and then pull the next day. then I hear about HIIT. and super sets.

I ask because I am about to go sign up for a gym membership and want to start working out, but I don't know where to begin or how to write out a work out plan since there are so many different ways to work out.

I am 5'4", 213 lbs, 17.5 neck, 46 shoulder to shoulder width. I am tired of looking so Damn stalky. I just want to look thin and really toned/ ripped. I don't really care to add mass since I've had mass all my life. any pointers on where to start?