The old town is pedestrianised and small enough to walk in every direction. Expect steep stone steps — flat shoes are a good idea, and rolling suitcases are a curse. City buses (lines 1, 2 and 3 are useful) connect the centre with Banj beach, Solaris and the outer neighbourhoods; pay the driver in cash.
For Krka National Park and other day trips, Autotrans and local buses leave from the main bus station. Car hire is widely available but parking in the old town is restricted; use the public car park near the marina and walk in.