Come really, really hungry.
That's the best advice I can give to anyone that wants to visit Hash House a Go Go. You will have more food on your plate than you can comprehend in a glance. Galaxies have been known to be smaller. The gravitational pull of the chicken and waffles may trap you in its orbit, forcing you to consume the chicken just to have a chance to escape intact... not that you'll mind doing so.
We've been to HHaGG multiple times for both breakfast, brunch, and lunch, and have never run into a meal we didn't like. Their reliance on potatoes as a filler sometimes borders on the crazy however. I'm tempted to ask for my next meal without any potatoes, if it's listed as an ingredient.
The meals we've experienced are the stuffed burgers, fried green tomatoes, chicken and waffles (with strips of bacon through the waffles), the chicken pot pie, the home-made corn beef hash, and some of the specials. The chicken soup was also very flavorful.
I can't think of anything I'd improve on when it comes to the food. Just remember that your eyes are larger than your stomach. No one's going to think less of you if you suggest splitting an entree here!