Tips on Seat Sales:
1. Best way to know there's a seat sale is through Twitter. Follow those airline accounts to score those cheap flights! @cebupacificair @flyPAL @ZestAirZ2 @airphilexpress @AirAsia
2. Have a ready list of places you want to visit on-hand. Seats are being booked as you ponder where to go. Also, you and your companions can share scouting the dates and flights for different locations you all want to visit. Makes it easier than deciding on-hand where you want to go. Saves you time and regret (for not getting the flight). 
3. Know the taxes included. Your base fare does not translate to your total airfare. Review every detail. You might end up paying so much because of the baggage costs, travel insurance, donations, etc. In short, thread slowly but surely.
4. (as informed by my friend), Cebu Pacific tends to overbook their flights by 20%. So make sure once you've booked yourself, arrive early at the airport to check-in.
5. Sometimes, impulsiveness can take you places. So if you have the money, then book a weekend at an unfamiliar place and discover something new.


Let me know if you have your rules/tips during seat sales! :)