When it comes to buying laptop bags, figure out what you need it to do before you go shopping.
The first thing you need to choose is the laptop size. Is your laptop computer size about 15 inches? Then remember you will need to keep all the laptop cords and other accessories with the laptop, so don't buy just a 15" laptop bag - go little bit bigger than that.
Secondly, consider the style of the laptop bag - what do you want it to reflect? Some peoples like a very casual style and some wants something with a professional look that matches their business or services.
If you are student and you want to carry some books and other papers along with your laptop, a good choice might be a rucksack bag. And for the fashion minded you can even get a colored bags and decorated laptop bags.
Third area of concern is the material the laptop bag is made of. Depending upon your preference, some people like leather and some like nylon. There are other fabrics, but find something that will wear well, but look good over time.
Fourth and last thing to keep in mind is how much interior space do you want your laptop bag to have. Beyond the actual laptop computer and its accessories, you might want to carry other items in the bag. Briefcase type laptop bags have lots of compartments and pockets to hold your files and other paper work and business cards and pens. If you don't like to carry two briefcases, get a bigger laptop bag which will do double duty as a briefcase as well.
For students, a laptop rucksack which can carry their books and water bottle along with the laptop maybe a good idea. Just make sure the other items in your bag don't damage the laptop!