I was worried when we got Caeda, since she's a Swissy, I was SO worried about the whole "big dog" thing. All I can say is that I'm glad she's a runt, all 65lbs heh....
I second Amaryllis's advice, train train train, be especially sticky on not jumping on people, leash walking and bite inhibition. I would put these above "sit" and almost above recall. Recall is of course super important, but that is in general for all dogs. Be prepared to put work into stopping counter surfing

General impulse control is really important, check out the Doggy Zen sticky, I think Caeda learned a lot from those exercises.
You might want to decide now if you're going to be ok with a big dog on your furniture, in your bed etc. It would be kind of mean to be ok with it as a puppy then one day "sorry, you're too big", it'll just create confusion. Same goes with rough play, decide limits now for what you expect you'll be ok with in the future.
HUGE thing....SOCIALIZE!!! If your dog is well socialized to lots of people, animals and situations it may be less prone to feel the need to break out of those nice leash manners and drag you 100 feet.
If you see any issues like guarding or aggression try to deal with the behaviour early, so it doesn't turn into a problem when the dog is too big to control, though try not to mistake puppy rough play with aggression, which many do (I almost did in a few cases). I did have a guarding incident and I got on it right away and I'm happy to say it isn't a problem now.
I also wholeheartedly agree do not use violence, intimidation or a heavy handed approach. A clicker works great, or a marker word. The Kikopup channel on Youtube is great for training techniques.
You might also want to consider dietary requirements for a larger breed, and of course, as above exercise!!! An unruly small dog is annoying, an unruly large one (or even medium like Caeda) has the potential to wreck your house.
Do not leave your dog on a tether unattended, no brainer for any dog, but with a strong dog collars can break (Caeda broke one at 3 months!), and so can tethers, plus the potential for trachea damage. Leashes (flexi's expecially) can break too!
Good luck!!!
Oh, and haha NikoBellic

bad joke, but I still laughed.