Keywords or tags are used by the LightRocket search engine to retrieve files. So if you don’t add keywords to your files, the chances are they won’t be found, even if they are searchable on LightRocket and/or your site. And if your files can’t be found, they can’t be sold.
Keywording (or tagging as it's also known) isn’t much fun but if you keep it simple it can be quick and effective.
Less is more where keywording is concerned. Only add keywords that are strictly relevant to the core meaning of your file. Always imagine yourself into the position of a user searching for a files; imagine if you typed a keyword into the LightRocket search box, would you be happy to see your file come up as a result.
Irrelevant keywords reduce the precision of the search engine and will end up disappointing clients.
You might want to use LightRocket's tagging thesaurus which is accessible by clicking on the 'thesaurus' button underneath the keyword field on the Edit File Info panel. Note that Launchpad account holders can only use the thesaurus 5 times a day and that the full thesaurus is only accessible to Power plan members.