01Cash vs. card
Hotels, villas, larger restaurants and beach clubs in tourist areas generally take cards without issue. Step down to a local warung, a small shop, or anywhere outside the main tourist strips, and cash is often the only option. Carrying a moderate amount of rupiah at all times is the practical default, topped up as needed.
02ATMs & fees
ATMs are common in South Bali and Ubud, less so further out. Fees vary a lot by bank — some charge a flat fee per withdrawal on top of whatever your home bank charges, so it's worth comparing a couple of machines rather than using the first one you see. Withdrawing larger amounts less often minimises the per-transaction fee hit.
03SIM cards & eSIMs
Local providers (Telkomsel has the best rural coverage; XL and Smartfren are solid budget options in populated areas) sell tourist SIMs with generous data allowances cheaply. Airport counters are the most convenient but usually the most expensive — a phone shop in town costs less for the same package. If your phone supports eSIM, several providers now offer digital plans you can activate before you even land.
04Tipping norms
Tipping isn't the deeply embedded custom it is in, say, the US — it's not expected everywhere, but it's genuinely appreciated and increasingly common in tourist-facing spots. Rounding up for a driver, leaving small change at a warung, or 10% at a nicer restaurant (check if service is already included first) all land well.