Sure, you may want a dog, but that isn't the only criteria that should go into your thoughts. There are more reasons NOT to have a dog than there are to get one, so knowing if you're really ready to get a dog revolves around a few key things.
First of all, is your home ready for a dog? If you have hard wood floors, a non-fenced yard, or stairs in your house, it may be more difficult to have a dog than you think. Before you get a dog, fence in that yard, block off staircases or make them dog-friendly if they go outside, and get rugs for those traffic areas if you want to keep your hard wood in good condition.
Do you have the time for a dog? You have to clean up after your pooch, take him for walks, play with him, take him to the vet, etc. If you can't dedicate a half hour (at least) a day to just giving your dog attention, you likely aren't ready for a dog. Sorry.
Finally, dogs are expensive. Most people forget about buying food, vet costs (including getting your dog fixed) and other costs associated with getting a dog. People spend on average nearly $250 on their dogs a year, just at the vet!!! If you're going to get a dog, keep this in mind, as he/she will likely cost you lots of money for the next several years.
Before you get a dog, think of the reasons not to get one before you jump ahead of yourself. This way, you will know if you are truly commited to getting a dog or not, and will make the right decision more easily.