Let's say I have a website called books.com where I sell books. I've read on Redirecting different domains to your main site that it's not a bad idea to register another domain that does a 301 redirect to my website, like booksforsale.com. Now, say I want to only target a specific category withing my website, like books.com/sci-fi/ so I register sci-fi-books.com and do a 301 redirect. Would this improve my search rankings? Thanks.