It's okay to customise the wrong sub! I did too the first time and subway employees won't judge you for your preferences. I recommend Italian Herbs and Cheese Bread (toasted) and Old English Cheese. Then, choose your favourite type of meat, salads, and sauce! for example, in terms of salads, I already know I don't like carrots and onions so I avoid putting them in my Sub. Also, if you feel more comfortable ordering online, you can do that if that option is available in your area.