Check the limits
Minimum and maximum amounts may differ for deposits and withdrawals. Do not assume that a method available for deposits also supports withdrawals.
Account holder details
Many operators require the bank account or wallet holder's details to match the player's account details. Using someone else's payment method may trigger additional verification.
Processing and arrival times
The stated processing time and the actual time for funds to arrive are two different things. The bank, payment provider and KYC procedure can affect the timing.
Keep confirmations
For larger or problematic transactions, keep the payment ID, date, amount and your support contact history.