I was wanting to buy a used car, but no established credit + bonus?

Hello everyone,

After paying this college off, I will be able to go back and get my education, but with 5 people in the house (1 goes to school in a different city, and 3 of us work in different cities) it's always been a challenge to schedule everything. I was wanting to buy a used car to make it easier for around the $9,000 - $10,000 mark, but this would be my first car. Thing is, I don't have any established credit and my mom's credit is poor so I wouldn't have a cosigner. What I was wanting to do is put about $3,000 down on it (Since I do work), and pay it off monthly, but I'm not sure if that's how it works exactly? Could someone explain/tell me if that will work or not or is it more difficult then this? Thanks in advance

Bonus: I was wanting to get a used Smart Car. How many miles are those cars good for? I've seen some on sale for 6,000 miles and some for 50,000 miles. Thanks also in advance