Keep travel simple if possible by sticking to a single flight and a short transfer.
Long haul travel can work fine - night flights are easier as children will sleep and need less entertaining than during the day.
It is worth paying the extra on the no-frill airlines to board first as most of these Carriers no longer offer priority boarding for those with children, but only to those who have paid for this.
Children are not allowed to sit in the emergency exit seats.
Under 2's can travel on your lap but think carefully on the size of your child and the length of flight as it can be hard work! An extra ticket may be worth the space and peace of mind although they will still have to sit on your lap during take-off/landing.
Rules for basinets (long haul flights schedule flights only) vary by airline so it is worth checking at the planning stage.
Check that all your passports are still within expiry date. Remember childrens passports are only valid for 5 years.