The flexibility of PriceLess and how you decide to track items is a great feature but can be daunting to know where to start. Generally speaking an item should be specific enough to give you meaningful price comparison data.
The question is often how specific to name an item? This is trickiest when there are different types of a common product such as cheese, milk, beef, etc.
Cheese has different styles and sources which greatly impacts its price. Comparing all these types of cheese in one 'Cheese' item likely won't be helpful unless you truly want to compare generic American Cheese with that fancy aged imported cheese that's 5x more expensive. So in this case you may have an item for 'Shredded Cheese' another for 'Goat Cheese' and one for 'Cheddar Cheese.' Then within each of these items you could have tags for 'organic', 'sale', 'imported', or 'aged'.
Think of tags as adjectives for an item. With the ability to filter by tags on the Item Detail page you could exclude prices marked as 'sale' to see what the best regular price was. Or exclude 'organic' to find the best conventional price for your favorite food.