Greetings from Poland to our European friends!
I participate in a hitchiking race from Warsaw to a campsite in Kalamitsi (Καλαμίτσι - south-east to the Thessaloniki), there are about 500 participants, mostly students. This will be our first time in Greece, therefore I ask to get rid of some doubts. How popular is this kind of transportation? Is it safe in Greece overall to travel like that (regarding the immigration situation)? Are locals fed up with tourists already or do they offer rides to foreigners sometimes? Are there any body signs that are an insult in Greece we might not be aware of? We wont cause much trouble as most of us are experienced in hitchhiking - last year we safely arrived to and got back from Rome so we look forward to have similar positive experience this year :)
Also me and my friend found out that we both have free time after the journey, and we are planning to visit Athens afterwards. We will arrive there on 8th of May and leave on 10th. How much is for the bus tickets? Is there any campsite in the city we might camp in (we aim for a student/budget trip and camping is pretty much what we are looking for and are comfy with)? Or maybe there is a youth/student organisation that wouldn't mind host us in their garden/dormitories for 3 nights?
Thanks a lot for any advice, and if you don't have any but are still here, cross fingers for a sunny weather :)

Short holiday in Athens/Hitchhiking in Greece