That's how I prepared and it turned out very well ;-)
First of all: Bali is safe – although Mount Agung erupted in November 2017, it remains calm and especially the other side of the island will still be safe even in the case of an eruption.
Photo: Mount Agung before eruption
1.) Check your vaccinations in advance
I started with getting vaccinations 3 months before my trip. Just went to a qualified doctor's office in Hamburg (http://www.impfcentrum.de/) and he told me what I needed:
• Japanese encephalitis (Japanische Enzephalitis)
• Rabies (Tollwut)
• Meningococcic (Meningokokken)
• Hepatitis A
But that really depends on which vaccinations you already got in the past.
Some vaccines need more than one treatment – I went to the doctor three times and paid 840€ in total. Most of the health insurances absorb the costs. You should probably check with them in advance, but mine is really supportive and paid me back super quick.
Bali is not a malarial-country, but I guess it's good to be prepared for that, also if you plan on visiting different islands/countries. So I brought Malarone with me, which your doc will prescribe.
2.) Check your health insurance for foreign countries
I've got an insurance agent who supports me with all the insurances needed. (Hamburg peeps, send me a message if you need a good one.)
Read carefully through the insurance paper and check on what they pay for and for how long.
For me it's important, that they'd fly me back home to Germany in case of a longer hospital stay.
It doesn't cost much to get an insurance, so I highly recommend to get one. You will need it, when you don't have one – and won't need it if you got one.
3.) Book a flight
If you're not depending on a specific date, I'd suggest to try skyscanner.com. You can check prices in a specific month and compare them.
You can get a visa for 60 days in advance if you plan on staying longer. Just visit the indonesian embassy in your hometown.
But there is no need to, as you can get visa on arrival (VOA) for either 60 days (35$ - make sure you bring a credit card or cash) or 30 days for free. Be careful with choosing the flights and count the days.
5.) Fill your first-aid-kit
It's always good to be prepared and bring the meds you might need. Such as:
• charcoal tablets or Psyllium seed husks and electrolytes powder in case of diarrhea.
• Pantoprazol for pyrosis (Sodbrennen)
• pain killers
• meds you always use, when getting a cold
Bali has good pharmacies (no worries), but: first of all you don't wanna rush to a pharmacy, when you got diarrhea (you really don't want to) and second it's good when you already know your meds and your body is used to them. #noexperiments
5.) Get excited!
Photo: Flowing temple in Bedugul
What to pack – What to bring
• mosquito repellent if you get bitten easily (I highly recommend Nobite or any other repellent with the active substance "Deet")
• for girls: tampons or menstrual cups as tampons are crazy expensive on Bali
• if you're staying longer or have friends living on Bali: BRING WINE OR LIQUOR!!! Way to expensive here! (You are allowed to bring 1 liter alcohol per adult)