At a guess, we all started out with what now seems a terrifying level of naievity.
For me, I'd read in wankmags like Playbirds or Whitehouse about massage parlours. The adverts towards the back were fairly explicit, but all London based.
At the time, I worked in the city centre, and used to get the bus there and back. One morning, the bus got to a few hundred yards of my stop, and then broke down. We all got off to walk the remainder.
As I was usually on the bus, I'd never noticed the piece of paper stapled to the door of an otherwise shuttered shop, which said "**name forgotten**'s massage parlour. Ring xxxxxx for appointment".
So, quite furtively, l noted the (landlines, no mobiles back in 1976!)number and at lunchtime rang from a call box and booked in.
Arrived and paid something like £5 fee for a sauna and massage.
Taken upstairs to a big room, massage table laid out, and a big wooden sauna to one side. Shown a locker and told to undress, lock my stuff away and wait in the sauna
Did so, and stepped into a sauna for the first time in my life. God it felt hot! On the bench was a stack of magazines. Sitting there sweltering l picked one up. It was a Danish porn mag, called "New Cunts". I was firstly astonished at the title, and then as l leafed through it, at the pictures of gorgeous girls, all with smooth shaved pussies ( that was New Cunts ethos,) sucking, fucking and getting cum spattered.
Of course l quickly got a stonking stiffy. At that moment the sauna door opened and in stepped a pretty, slim, mixed race girl who introduced herself as Monica the masseuse. She had on a loose cotton top, which she immediately removed, to sit, naked apart from little panties, next to me.
After a couple of minutes idle chat, she grabbed my cock and said "I think you're ready for your massage now".
She led me, by the cock to the massage table where she immediately started sucking me off.
I don't remember how much l paid, but that first experience is still fresh in the memory.