Are there US-based Costco shoppers here?

I wasn’t sure how to flair this: I am seeking advice. I finally decided to get a membership and have perused YouTube for info on how to shop at Costco and any tips or tricks. For example, I went this week to check out the warehouse and did not know that I could order online and have things delivered!

Update: So thanks for all the responses, lots of engagement! Any more tips on Costco shopping? Like, fortunately I did notice people bringing bags in and had some in my car. Where do people find those boxes? There was a checkout (rather than self checkout) which I used and let them know I was a newby so they explained things like scanning my member card again at checkout