Indians who traveled abroad for the first time — what confused you the most / what do you wish you knew?

This is my first time travelling abroad. I have not even started the paperwork yet. So I thought lets get everything right from the get go.

I don't know anything about anything about travelling abroad. Please give me advice about listed down topics, and what confused you the most/what do you wish you knew before your 1st international trip?

1. Flight tickets
2. Important documents that I need
3. Passports,
4. Visas/transit visas
5. Mobile roaming
6. Forex/ Currency Issues
7. Travel Insurance

P.S. These are some of the things I noted on top of my mind. If there is anything else I need to look out for, please feel free to tell me about them as well