Sorting items by category is possible using a spreadsheet or a deck of color-coded index cards if you do not wish to use a computer. If the list of items is long, a computer spreadsheet is most likely the quickest method.
If you have Microsoft Excel, just enter your list of items in a column, and create a second column with the category of each item. Then, highlight both columns, and sort them alphabetically using the sort options in the data menu. Other spreadsheets have similar sorting capabilities.
If you prefer not to use a computer, the index card method is also effective. First, write each item on an index card. Next, choose a different color for each category, and highlight each card with the appropriate color. Finally, separate the cards into different stacks by color. You can also use colored index cards if you have some, or just label some small boxes for each category and put each card into the appropriate box.
There are many other creative approaches to categorization. For example, creating your own symbols or even using stamps or stickers to represent each category is a fun approach. If you have a cork bulletin board, you can divide it into sections for each category and pin each item in the correct section.