We’ve come a long way from the time when Amazon was that upstart website where you could buy books and CDs. Today the company has created a sprawling retail empire that sells just about anything, from cheese knives to statues of Bigfoot. Amazon has become so big that its annual blockbuster sale — Prime Day — draws comparisons to Black Friday, despite the fact that it consists of just one “store.’’

Prime Day, which this year is scheduled for Tuesday, July 11, is a daylong bacchanal of deals and discounts. Actually, this year, Amazon is stretching the day to 30 hours. The offers are staggered throughout the day, with new sale items made available every five minutes. It’s a format tailored to keep consumers engaged and ready to buy for hours, which means it can also be a format that lures deal-hungry shoppers into spending too much.

So here’s what you need to know if you want to take advantage of Prime Day while keeping your wits about you, and your credit card balance within reason:

You have to be a Amazon Prime member to participate. If you are not already enrolled, you can sign up for a free trial to take advantage of Prime Day deals — just remember to cancel afterward if you are not interested in paying $99 for the full year.

Preparation is half the battle. Take a moment to make a mental inventory — or better yet, a real list — of items you have been wanting or needing. It is harder to convince yourself that you need that case of grass-fed beef jerky if it’s not on the list right in front of you.

The first deals will roll out at 9 p.m. on July 10. You can find out about offers up to 24 hours ahead of time by going to the “Today’s Deals’’ page on Amazon.com and then clicking “upcoming’’ in the options bar on the left. If you download the Amazon app to your phone, you can also set up notifications to alert you when a deal you have your eye on is about to become active.

Once you’ve found what looks like a good bargain, take a minute to do a little research. Google the product, or check the price history on a tracking site like CamelCamelCamel.com (that is seriously what it is called). Amazon has a reputation for having the lowest prices, but that is just not always true.

Finally, give back. Start your shopping at smile.amazon.com and a portion of each purchase will be donated to a charity of your choice.

Have a consumer question or complaint? Reach Sarah Shemkus at seshemkus@gmail.com.