Step 1: Open the “Lists” drop-down menu and click on “create a list”

Step 2: Name your list and choose whether you would like it to be private or public

Step 3: Go to the Twitter profile page of the first person you would like to add to the list and add them by hitting the list icon at the top of their page and clicking on the list or lists you would like to add them to

Step 4: Repeat step 3 with each person you would like to add to the list

This is of course the manual approach to Twitter list building.  For an effortless and rapid-fire way to filter the people you follow or interact with you can also give our service, Formulists, a go ;).