When is it better to use custom fields instead of tags when organizing my Sell account?
Custom fields are ideal for storing and standardizing information in your leads, contacts, and deals. They are more organized and less susceptible to user error. Custom fields are also easily reported on.
Tags are ideal for filtering data and showing associations between your leads, contacts, and deals. Tags are also better for completing bulk actions as you can add and remove them in bulk using smart lists. However, tag reporting options are limited.
For more information on the uses of tags and custom fields in Sell, see the article: About tags and custom fields in Sell.