Poprad is a town in Slovakia. It is right by the High Tatras and it is easy to reach the mountains from this town. There are many trains that take you to the mountain villages from where you can find numerous different hikes. You can quite easily hitchhike to Poprad from Zilina or Banska Bystrica as many people are going to Poprad for hiking. From Poprad you can cross over to Poland and go on to Zakopane, Krakow, etc...
West towards Liptovský Mikuláš, Žilina
There is a gas station on the 18 road just after TESCO and near KIKA. You can either ask people on the gas station or hitchhike on the road, there is a place where cars can pull over. The best way to hitchhike here is probably with the two letter sign like LM,RK.
You can hitchhike at the intersection of national road 18 and the road Joliota Curie. The hospital is on Joliota Curie, so it is easy to find. At the southeast corner of the intersection there is a small merging lane where cars can pull over.
Hitchhiking from Poprad to Poland is not too difficult although it first might seem like it. However, I found out that by public transportation it might even take the whole day whereas I hitchhiked to Krakow in 4 hours. From the city center walk on the main street Stefánikova until you see the icehockey arena on the left side of the road. On the right side of the road you'll see a bus stop. Make a sign for Poland and keep your thumb up- there are a lot of cars passing by and many of them going to the towns nearby or Eastern Slovakia, but there are a lot of Polish people too and Slovaks going to Zakopane so the chances of getting a ride are good. I waited for about 15 minutes.