Is it safe and easy to drive in Croatia. Any tips?
Yes. Cross this off you list of things to worry about. Next question?
Aside from easy or safe, a car is of value or no value depending on the part of the country and where you want to visit. In Istria, I think a car would be great, maybe some parking issues in the larger towns, but overall it would have value. In the South, doing the typical Split, Hvar, Korcula, Dubrovnik spots; the need to take ferries and easy access to buses and ferries makes a car less useful, maybe a burden if you need to leave it parked for a great deal of the time.
Some more info would help. How are you getting to Croatia? Where are you planning to go? What time of year? How Many?