Continuing from the last post.
What weight is assigned to previous writing credits?
It depends. If you had a review of that new Italian restaurant published in your neighborhood newspaper, not a whole lot. If you've had a previous book published and then turned into a little-known 80's movie, a lot. Either way, we still have to like your writing.
And what if you don't have writing credits?
If your writing is good, it doesn't matter at all if you have no past experience in publication.
Should we mention if we read their blog or subscribe to their newsletter?
...I guess you could. It might help. It won't hurt.