Need help with puppy tugging on leash

I just got back from walking my dog. He's a 14 month old mix(mostly a terrier though). He's my first dog and I'm having a lot of trouble teaching him to not tug on the leash. I've been telling him very firmly no every time he does, and stopping for ten seconds before continuing. Tonight, I was doing that constantly, he'd tug, I'd stop, then start walking again and he'd tug again. This happened over and over. Eventually he did stop doing it as much, but when he did his business, he took off as he always did, and when I tried to stop him and pick up the result, he went into play mode, started running circles around me, and tugged the leash out of my hand. When I finally got the leash again, he was still in play mode. I had to pick him up and carry him back to my apartment because he kept trying to tug the leash out of my hand. Am I doing something wrong or is this just life with a puppy till he matures/till he learns the lessons I'm trying to teach?