Read the FIN before you sign
Use the standard pre-contract sheet to list every fee and compare offers side by side.
Set the full-balance repayment option
Paying the whole statement balance by the deadline avoids interest and the 4% stamp duty on it.
Avoid cash on credit
Use a debit card for cash withdrawals instead of a credit card cash advance.
Check late fees against Decree-Law 58/2013
Apart from default interest, the lender may charge only one recovery fee per overdue instalment, within the limits described above, and no other fee because of the delay.