Lucca? San Gimignano? When arriving are there signs pointing to where you are able to park? Just want to make sure. We'll be driving through multiple hill towns over a 2 day span (basing in Greve), however when visiting, wanted to make sure we were parking in the correct spot.
It will be easy to figure out when you're there. Many towns have lots (Assisi, San Gimignano, etc) and there will be signs pointing the way. At others, such as Cortona or Urbino, you just park on the road near the top (often it is pay parking).
I'm not sure when you are going, it may make a difference how difficult it is to get a parking space.
San Gimignano has a public parking lot conveniently located near the entrance to the old center. It would be hard to miss but might fill up in the summer.
At Lucca, we found a place to park just outside the walls without any trouble.
We visited both in October. San Gimignano had some crowds but not bad, Lucca was virtually empty.
Most towns have very good signage for public parking. Look for blue signs with white "P"s on them. Also learn what the signs for no entry and limited traffic zones look like.