The review is specific to packing your bags for an outing. The topic is actually very broad as you may be packing bags for various reasons - a short trip, office trip, long vacation, a vacation abroad, shifting home, a day picnic, an educational tour and so on. The packing needs can vary for each of these and some of my tips may apply for few and may not for others. I would try and keep them as generic as possible.
1. Keep it light: There are various advantages of keeping your luggage light and various disadvantages of making it heavy. I am not listing them all here. One tip to keep it light is - do not carry stuff which you can probably just buy at the spot you are traveling to. There are various ways you can make your bag less heavier - try and carry heavy items on yourself like a thick jacket or a pair of jeans.
2. Essentials: a-must! Having asked to keep it light in my first point, does not mean you leave out the essentials! What is an essential commodity is an individual’s choice, for instance for a photographer, a tripod stand & cam accessories would be a-must - no matter how heavy they are. For someone else, may be carrying 2/3 books may be important.
Generic essentials are those things which you would need in a normal day - so start thinking what are those items which you need from morning till you go to bed and most list would flow out instantly. Like starting from morning, toothbrush, paste, soap, inner wears, handkerchief, must-take medicines, glasses(if you wear one), sandals, light-weight bed sheet and so on.
3. Keep it small: work out minutely on each item so that your luggage is small and not heavy - for instance instead of dropping in the bag the available toothpaste at home - buy the smallest size of it which would last for your trip, choose sachet(of shampoo, oil etc) over bottle.
4. Work as per list: Always keep handy a list of items to carry - you can refer to it with every trip. You can choose items from it based on type of your trip. For instance you can give woolen wear a miss in case you are visiting a warm region.
5. Smart packing: Always ensure you pack well - do not stuff things, this will obviously take more space. For small items like medicines etc always best to carry a kit/plastic box. Instead of rolling items like scarfs, dupattas, try to spread them as less folded as possible on top of everything, once all stuff is packed - you would be amazed to see, the roll which you were not able to fit in earlier - has nicely fit in now. Put socks inside shoes, move sandals one into other, in case you are carry open ended items like a steel glass, try to stuff in small items inside it.
6. Valuables: Keep valuables(money, watches, Ray-ban, gold items etc) together in a small pouch which you can take care of and carry on yourself always.
7. Carry additional bags: It’s always a good idea to pack a small bag-pack, sling bag or a few plastic bags. Trust me they come handy in several ways - which you may have never even thought of even after planning for several hours.
8. Weather/terrain conditions: Carry stuff keeping in mind the terrain you are traveling to and weather conditions. For instance, it’s always good to carry a small fold-able umbrella if you suspect rains, or winter-wear, lip balms etc for colder regions.
9. Important items/documents: Keep the items you would need often on the outside compartment, like travel documents, books. Best to cover them in a plastic folder - just that it saves them from rain or any sort of accidental shower.
10. Entertainment: will usually depend on your kind of trip - however things like playing cards, some video/mp3 players, books, some games etc can be thought of.