Yes, I remember, in both the UK on on mainland Europe, that planning the place to hitch was very important - you had to give the drivers enough room to safely stop. Also, you had to be at a decent junction if heading long-distance - getting a lift a few miles was rarely worth it if you were going to end up in somewhere with much less traffic.
My favourite innovation was the cardboard sign covered with strong white plastic bag material. Then you could use a dry-wipe pen to write where you wanted to go and change it as you went along. Never could grasp why people wrote on cardboard after that...
Precisely what I used for almost a decade of hitching in Britain - along with a book that used to list all the best places to get lifts out of the busy conurbations (like how to get to the bottom of the M1). Mine was a piece of strong white cardboard covered in sticky backed plastic!
Regularly hitched between Southwick and South Cumbria. Out of the house at 6am, used to be at the other end at 3pm - not bad seeing as I lived over a mile up a track at the northern end. Managed it in two lifts once - firstly to Scratchwood, then to the Old Shoreham Road before the first chap had even ordered his cup of tea!
London was always the problem. Going northwards I used to get to the first tube, then out the Brent Cross. Coming south, get to Scratchwood services and have a sign saying 'Sussex-by-the-Sea' to get round the M25. Never failed.
Best place to hitch used to be Wales, where it was treated almost like public transport. Holland was also great, they used to have laybys with 'Lift Plaats' signs with a big thumb on them. Brilliant idea.
You couldn't get picked up along the A590 in Cumbria now - there's so much traffic no-one can pull over.
Shame really that a whole culture has simply disappeared.