I spent a lot of time wandering around the souks of Marrakesh. I ended up staying in the home of a gnawa musician in there for a while.  I got scammed into buying a carpet the first day. But I learned how to navigate the souks.
Best advice - get a sense of humor. You are a tourist in a tourist zone.  Get out of that zone and you will encounter more authentic Moroccan hospitality. But while in the zone - smile and plow forward with confidence - like you know where you are going - even if you don't.  Leave your stuff at home. Leave your phone in your pocket. Take very little money with you. The hustlers are trying to steer you to their uncle's carpet shop - in a beautiful cave like abode.  And they just want to serve you tea and show you a few carpets. And if you show any reaction, they will pull out dozens more that are sort of like the one that you raised an eyebrow at.  If you find yourself in that situation - and you will - down your tea, thank everyone and tell them you have an appointment at the police station.  So get in there and just wander about. Get lost. You'll eventually come out one side or another. And who is telling you a path is closed? Is it a young many who has made it his job seems to be to follow you about?  Ya, that's an annoying but harmless hustler. Smile and act like you don't understand but and that you do know more or less where you are heading.
Another thing you can do...when people ask where you are from? Just smile like you don't understand the question.  Keep it a mystery.  It's a fun little harmless game. 
If you get scammed into a buying a carpet you didn't want.... do better next time.

Two caveats - if it was a woman, then you probably should turn back. You might be heading into someone's private court yard where women are cooking or washing.  Women will not hustle you.  Or, if someone might warn you that you are heading towards the entrance of a small mosque - most mosque are closed to non-muslims.  But that guy will have a totally different vibe. He won't be trying to follow you around 'just to practice his english.'  (Totally avoid english student guy. He'll burn up your day.)

Another thing you can do - at night in the Jemma El Fnna - find some musicians you like and the pop a squat in the front row.  Have a bunch of coins. When they pass the bucket around, you can give a little more than the average Moroccan. You've now just made a dozen or so new friends that will watch you back.

Shopping is really hard. But ff you can spend the time to make some real friends you can have them help you buy a carpet. Even with them at your side... in their friends shop, there will be a long heated debate on what the price should be. It's hilarious. 'How do you expect me to feed my family!?'  And on and on... And then you make a deal and everyone smiles and shakes hands.

The one hustler that i really had to tell to fuck off was the guy that hustled me the first day. To him, i was his fish for life. 

That is the Moroccan hustle.  The US hustle is a $5 cup of coffee at Starbucks. Or some jerk off stepping in front of you so he can catch the next subway or cutting you off on the highway.  Moroccan's are very hospitable people. But the rules are different in the tourist zone.