Expect the worse. Deliberately left 30% of the luggage behind in Jeddah because the plane was overweight. No Eid gifts for the family. Part of the luggage arrived in Islamabad after my return and was picked up by my family. Part of my luggage still missing more than 3 weeks after my journey. Customer service unresponsive and has no clue how to deal with the situation. The lower fare definitely not worth the hassle...
Weigh your luggage at home: Avoid excess baggage charges by weighing your luggage at home and trying to stay under the weight limit (15 or 25 kilos per checked-in bag, depending on the airline). If you exceed the weight limit, you may be asked to pay 10-15E per extra kilo. If your luggage is overweight and you can't leave anything else at home, it may be a good idea for you to take a hand baggage. But be careful: you need to check the weight limits for your hand luggage too!