Research your project, the internet and YouTube are great

There are some knowledgable employees at home improvement stores. There are many employees who have no idea what they are talking about. 

Shop around, if you find. what you are looking for at an other store, Home Depot will match or beat that price.

Barter. Prices aren’t fixed. Most employees can move down as much as $50 on a price. Managers can often do better than that. Find store display models and slightly damaged items and offer to buy it at a big reduction

Learn how to get rid of your construction garbage. Home improvement creates garbage and lots of it. Learn how to take stuff to your local landfill.