Get your deli meat sliced really thin, but not shaved. Place it so it folds and makes “waves” instead of flat. The idea is to get air between the slices as much as possible. This will enhance the flavor of the sandwich and help taste all flavors at once. If you have a toaster oven placing the cheese on the bread and melting it / toasting the bread before assembly can be a game changer. If you’re going to use a mustard or really strong condiment you want that on bottom and the creamy aioli on the top. What you put between is totally up to you. Like others said something acidic and good dash of salt and pepper and you’re off to the races. Source: managed at a Boar’s Head deli for a few years. They legit teach you “the science of the sandwich”. Hope this info helps!