How long are you going to be on your own and in a situation that allows you to keep the dog. A 10-15 year commitment is what you'll be making and you want to be sure that you'll be able to stick with it before getting one.
In the time I've had my current dog I have gotten married, moved a few times, and had 2 kids. Every decision we've made we have had to take the dog into consideration. We have missed out on houses we wanted because of no dog policies, and ended up living in ones we would have not considered had it not been needed. I had a pediatrician tell me I shouldn't be keeping a large dog with small children and should look into getting rid of her.... We got rid of the pediatrician instead....
Point is if your unsure of how your ability to commit long term maybe put it off until your sure of that, or look into adopting an older dog.