Elevate your sandwich-making skills with tips and tricks from the pros. (iStock)

Today is National Sandwich Day, making it a good excuse to upgrade your desk lunch. We asked Gilli Rozynek, owner of New York City's Brown Bag Sandwich Co. , to share tips for building better sandwiches at home, along with the kitchen tools she uses to chop, toast, slice and store them.

The whole is greater than the sum of its parts

"One of the biggest mistakes people make is stacking a bunch of delicious ingredients together without thinking about how they’ll actually eat them," Rozynek says. "You might get the meat in one bite, the lettuce in the next and the sauce at the end.…