How can I avoid going overdrawn?

Preventative measures to avoid going overdrawn include agreeing a new overdraft limit with your bank, using a Basic Bank Account (which does not allow overdrawing) or budgeting (so you can account for all your income and outgoings).

Source: Direct.Gov

How to avoid unfair overdraft fees @ Moneywise
Excerpt: Review your direct debits. One of the most common causes for people going overdrawn is badly timed direct debits – for example, your mobile phone bill coming out just before payday. One way to avoid this scenario is to set up direct debit payments for as soon after payday as you can, while there is still plenty of cash in your account. If you can’t move a direct debit then make sure you have enough money to pay it without going overdrawn.