Be on time! Check in from 22 hours before departure online or by mobile, but always no later than 30 minutes before your flight leaves. Be at the gate no later than 20 minutes before departure. Note that when your flight is closed for check-in 30 minutes before departure, your pre-booked seat will be released. More on check-in deadlines here
If you are denied boarding or if your flight is cancelled or delayed for at least two hours, ask at the check-in counter or boarding gate for the text stating your rights, particularly with regard to compensation and assistance.