Favorite city to visit in Spain is Toledo.

I never buy a sim card. If you have an Iphone you can use iMessage with WiFi.

I have a money belt but I rarely use it. I have a jacket and a backpack with inside pockets that I prefer to use.

Rental car isn't a bad idea if you're covering a lot of ground. Keep in mind though that a lot of old cities aren't car friendly.

Leave the debit card at home. Bring a Credit Card (make sure it's chipped). Pull out some local currency for street purchases.