Harry Potter and Twilight are two mammoth author brands. When anyone says the name Harry Potter, one inevitably thinks of Harry's author, J.K. Rowling. The same is true of Twilight; that single word forever owns Stephenie Meyer. Both are series titles; Rowling used Harry Potter as a title prefix for her global-bestselling novels, while Twilight began as the title of Meyer's first novel and went on to become the brand name for her entire series, the movies, the merchandising, etc.
On a far more modest level I've branded and rebranded my works and myself with multiple titles: Darkyn, PBW and StarDoc have proven to be the most popular. I coined Darkyn and StarDoc; PBW is shorthand for my blog title. Single, easy-to-remember words can be powerful brands for lesser-known authors, especially multi-genre/multi-series writers like me. You may not remember which pseudonym I'm currently using, but PBW will stick to the roof of your mind because 1) it's extremely short, 2) it's simple and 3) it's an identifier: PBW, aka Paperback Writer, aka that chick with the writing blog.
Branding is an art all on its own, and you can spend years chasing the right word(s) that define you and/or your writing. Your first idea may not be your best, either. Before inspiration struck me one night in the shower, I called my SF medical adventure stories the Border FreeClinic series. Back in 1998, I dubbed my Darkyn tales the Darkling stories (which wasn't bad; it simply wasn't right.)
For novel branding, I prefer brand words that tell a story in a single glance. Star + Doc = galactic physician. Dark + Kyn = shadowy relatives. When I had to come up with a title for the books my publisher had me write as a spin off of the Darkyn series, I worked for weeks combining and recombining words without success. Finally I threw out everything and meditated on it. I knew I wanted to use Kyn for the connection to the original series, but what to pair with it? Who were these characters? I knew them as ordinary mortals with extraordinary abilities whom the Darkyn should really dread. And that was when the light bulb came on; dread was the word I needed to complete the series brand. Kyn + dread - a = Kyndred.
To find brands for your works or yourself, the best place to start is with word lists. Begin jotting down every word that describes you, your stories, your style, or anything that is strongly related to you or what you write. You don't have to automatically go for one-word or simple branding; the keyword here is memorable. For example, you may not know who Daniel Handler is until you hear his pseudonym: Lemony Snicket. Marjorie Liu's series title Dirk & Steele invokes images of honed, bladed weapons (which aptly applies to her characters.) Patricia Briggs's Alpha and Omega pulls double duty by reflecting on the soup-to-nuts hierarchy of her werewolf pack's social structure as well as the unusual relationship between her protagonists, an alpha and an omega werewolf.
Don't instantly discount your pseudonym as a brand - I can't ever recall any of the titles of author Carl Hiassen's novels, but I remember his name due to the surname. I do the same with Susan Elizabeth Phillips because hers is probably the longest author name I know, plus it's as elegant as her writing.
If you can't think of memorable words off the top of your head, hit the thesaurus and make some synonym lists based on your keywords. Focus on words that invoke an immediate emotional reaction, or that invoke instant imagery. Once you have a couple of pages, play with the words by pairing them with each other as new compound words, changing the spelling slightly and/or recombining parts of them to form coined compounds. You can also feed your lists to Wordle and generate a cloud that will shuffle the words around and create interesting groupings; I find this works best if you select a horizontal or mostly horizontal appearance so that you get a more linear cloud.
To run a fun test of how memorable your brand is, add it to a list of similar words, show it to someone for a minute, take the list away from them and ask them which word they remember first. If they say your brand word(s), it's probably the winner.