How should I organize my products and services to be placed on my pages?

As a matter of website design preparation, the first step would be to think about and note how one should categorize all the products and services at your website. While defining categories, one must keep in mind that it makes a lot of sense to divide all the products and services into separate sections and divide each section into categories, any category into sub-categories and sub-categories into sub-subcategories and so on.. broken down to as many levels as possible. So the server takes less time to process and displays the items (of a sub-category) to the visitors much faster. In other words, the fewer number of items in a sub-category the better. This way, it will be very easy for the visitor to find an item and for the server to process and display it much quicker. 

As a result the potential customer's valuable time is not wasted, they are more likely to stay on your website, find their desired items and make a purchase. 

The following could be one incomplete example of many possible ways of categorizing items in a clothing store. 

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Clothes (root category)
      - Men (a category belonging to root category)
                    -- Shirts (sub-category of Men category)
                                  --- Dress shirts (sub-category of Shirts sub-category)
                                  --- Tshirts (sub-category of Shirts sub-category)
                                  --- Casual shirts (sub-category of Shirts sub-category)
                                  --- Other shirts (sub-category of Shirts sub-category)

                    -- Sweaters (sub-category of Men category)
                                  --- Wool Sweaters (sub-category of Sweaters sub-category)
                                  --- Cotton Sweaters (sub-category of Sweaters sub-category)
                                  --- Other Sweaters (sub-category of Sweaters sub-category)                                            

                    -- Pants
                                     --- Dress pants
                                     --- Gins
                   

                    -- Shoes
                                     --- Dress shoes
                                     --- Sport shoes
                                     --- Sneakers           
                    

                    -- Hats
                    

                    -- Underwear
                    

                    -- Socks
                    

                    -- Ties
                                     --- bow ties
                                     --- regular tie

- Women (a category belonging to root category)
                    -- Sub-levels broken down similar to Men  category

- Children (a category belonging to root category)
            

                    -- Boys
                                     ---
                                     ---
                    -- Girls
                                     ---
                                      ---
                    -- Infants
                                     ---