Besides using fresh ingredients, I believe the essence of a good Pad Thai is in its sauce. Best of all, it requires only 4 ingredients (minus the msg and other preservatives found in the ready-made version)!
You could prepare the sauce ahead of time and store in the fridge for up to one month.
1 ½ cup (about 3 pieces) Thai palm sugar – chopped (replace with brown sugar if unavailable)
1 cup white sugar
1 cup Thai fish sauce
1 cup Tamarind concentrate / paste
Add all the ingredients in a saucepan and bring to boil. Reduce to low heat and simmer for 10 mins. Let it cool before storing in an air-tight container.