All pho is not the same.
I grew up in a tiny house in Southern California packed to the brim with my family. In Vietnam my family owned and operated a pho house in Saigon. Every Saturday I saw my mother or grandfather create perfection from broth that had been carefully prepared days ago. The broth permeated my house at the end of the week giving random people passing our house watering mouths.
I consider myself a pho connoisseur. You can be one too. The family secret for the broth goes to my grave.
First is the place you decide to visit. Go deep into your local Chinatown and you might find a little Saigon. Pho joints are everywhere and tend to conglomerate together. A fun little experiment is to go to a different everyday. Try not to base too much on the looks of the place. The dirtier looking ones are still there for a reason. The ones that cater to a more "western" crowd tend to have poorer versions.
First, notice the plate of veggies that they give you. You should notice the sweet Thai basil, bean sprouts, and lime, the triad of basic pho vegetables. Depending on where you are you might see mint, cilantro, chilies and various other greens. At a good pho joint you'll notice that everything on the plate is fresh and recently cut. The sprouts should be crisp and not soggy at all. The basil stems should not be brown.
When the steamy bowls finally get to you first thing you should do is sip the broth. It should be rich, with no one flavor overpowering it. Avoid putting in the usual combination of sauces into it, as the flavor can run the gamut as you go to different joints. Even at restaurants you frequent the broth will change in overall taste to a tongue that is properly trained. The sauces you put in are mostly personal preferences. In general if the broth tastes like it needs some salt, add a bit of fish sauce. Be careful, it's very powerful. Try not to add too much hoisin or Sriracha because you want pho, not hoisin/Sriracha soup. Hoisin is dark brown and has a sweet taste to it. It is useful sometimes as a dipping sauce for meat if you don't want the broth to taste entirely of it. Sriracha is what mdlever called Uc. It has a distinctive, garlicky taste. (Uc actually means any spicy ingredient in Viet) Sometimes there will be some ground up chilies in oil. If you are so inclined be sure to try to get in as little oil in as possible. Now add your basil, lime juice and sprouts. Mix in bowl.
The noodles should never be clumped together. Unskilled cooks will often cook the noodles too long in the soup creating a starchy mess for the broth. On the other hand when eating only the the noodles, they should have the essence of the broth. As you eat at different places you will notice that the noodles have much to do with the overall experience even though they might have the least amount of flavor.
The meat selection, depending on which bowl you have selected, is delicious. Go ahead and try every different cut of beef even if it sounds disgusting. Flank, tripe, brisket, fatty brisket, and meatballs are things you might find on the menu, among others.
Vietnamese coffee is a good compliment to a large bowl of pho, iced or hot. It will help you blend in if you're a neophyte.
I have found that the best way to teach others how to pronounce pho is to say "fuh" like it's a question. "fuuhh?" If you're not Vietnamese, start asking how to order things on the menu. You'll never understand how much servers will smile if you come in speaking English then order everything in Viet. Now go get some!