The garnish and presentation possibilities are endless but the most important part of the meal is the broth! If the broth is tasty then you're all set and everything that gets dunked in there absorbs that yummy flavour.
At the asian supermarkets there are hot pot mix packets available but I like to make my own.
Best to make the stock many hours in advance.
Here is a delightful video presentation on making a yummy stock, I used it for my inspiration and make both pho and hot pot frequently in my home.