With cheaper flights and budget airlines, people are flying everywhere. So packing a suitcase is a necessary chore but can be done effectively. These are tips that I've amassed through experience. Of course if you're not flying to where you're going, it's still useful to pack as if you are to minimise space and hassle (especially if you have to travel on subways or buses).
Step 1: Choosing the luggage
I'm writing this from a UK-centric standpoint as that's what I have most experience with. This Ible will deal with flying on a plane with one piece of hold luggage / checked luggage / stuff that goes under the plane. There'll also be an additional bit for the ever tricky hand luggage.
I'm using this small hard-shell suitcase in this instance because I'm only going away for a few days. Although if you're going away for longer, take a big case. If you're flying budget airlines (in Europe these are easyJet, BMI Baby, RyanAir etc.) then there is a limit of approximately 20kg per bag. Once you've chosen your preferred bag, move onto the next stage.