Don't know what to do in case you get a letter, as in such event it's most likely that is already too late, but this is at least what you shouldn't do in order to stay under the radar:
-The most important one: Do not provide a bank any of your non-local addresses, regardless means ( ie paper,phone, electronic or any other form). This goes for your domicile addres, temporary adress, PO box or just about anything else, that is not local. The only address you should provide is your local address.
-Do not transfer bucks from a local account to your account in your domicile country. Do not do this.
-Do not call a bank via phone numbers, which aren't local ones. Buy a local phone number (SIM) and try to use it for bank calls only, or call from local phone boxes. In short, use local phones.
- When talking with bank's personell, don't tell them anything except local information. In particular guys from customer support like to ask stuff which you don't want them to know.
-Do not provide a bank e-mails, which are not local. Altough generic domains like .com shouldn't be an issue, the domains which are tied to specific country, e.g. '.de', '.at', '.it' are red flags, in case they differ from local domain. If you have to provide email, provide it with local domain -e.g. if your bank account is opened in Germany, stick with myemailname@domain.de.
In my opinion these are the most important ones. One can find more CRS document, as there is the whole procedure explained, altough it's a lot of law terminology, so prepare for googling.
And one more thing - I'm not favouring tax evasion, but if you're working your student a** off for savings, which your domicile country wants to wipe them all without even considering reasonable deductions, then you'll have to stay under the radar. If your domicile country has similar tax rate as the country, where you work, then the size of tax obligation isn't really problem, but if your domicile country has way significant tax rate as country where you work, and if your domicile country doesn't include your expenses in deductions, then you're in troubles.