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...
Fly during working days: As many passengers prefer to fly on week-ends, week-end tickets sell first. If you don't book your trip well in advance (2-3 months before) you may notice, for example, that Thursday flights are cheaper than Sunday flights. Some low cost carriers have special promotions on the flights during the week.