Székesfehérvár

Székesfehérvár is a town in Hungary located at the M7 between Budapest and Balaton.

hitching to the north side of Balaton

You should walk to the north of town, following Palotai ut or Szent Florian Körüt. At the end of the town, there is a roundabout where the only main road on the north side of Balaton starts. Use a sign, saying Veszprem. Once you're in the rural areas you can hitch with a thumb everywhere, people there are very likely to pick you up.

hitching to Budapest from the north side of the Balaton

From Veszprem, Varpalota on route 8:

There is a bypass road east of the town, where the route 8 ends. There is a sign to the motorway (southwards): don't take that way, the cars all head to Balaton. To get to Budapest get through the city centre (maybe take a local bus), or take the northern bypass. Find the "Seregelyesi ut" or later: route 62 to Borgond (Börgönd), there is a petrol station on the highway, where 62 crosses it. The highway has much bigger traffic, I don't recommend the old road "7es ut, Route 7" with its mostly local traffic via the urbanized Velencei to/lake. Good luck!