Do you think i can still join the military.?

I am interested in joining the military again. I tried joining the military three years ago. However i decided i wasn't ready. So i went to community college for 2 years. Now i am rethinking about joining. What are my chances of getting in? I am thinking about the marines or coast guards. I got relatives who are in there and they said it would be a smart choice. I would like to join posthaste. I was in the dep twice. They said if i quit they would put me on some kind of blacklist to where i could never get in again. So i am scared that if i try i would be wasting the time of the recruiters. I realize i made a bad decision for not going into the military the first time. But i was immature and 17. So I am hoping they will give me another chance.