Linking to or promoting competing story sites anywhere on Lush is disallowed, and may result in your account being banned.
Self explanatory. If you have your own amateur site, non-commercial blog, that is perfectly fine, and you may put a link to that in your profile area.
Putting a line at the start of your stories, or in your profile linking out to a competitor's website is downright rude apart from anything else.
Would you go into a local bar, and start telling the regulars how good the pub up the road is? You'd soon be shown the door. The same principle and outcome will result here.