If you don't have anything nice to say, don't say anything at all. That phrase applies to blogging too! If you don't have anything of value to add to your blog then don't post crap! Now, if you have a schedule for your blog then you are going to want to work ahead and post items in advance (blogger and wordpress both have features which allow you to automatically post from a queue).
Quality is the biggest part of both attracting an audience and making google like your site. By 'like' I mean index it for the keywords you include in your title and in most paragraphs of your article. For instance, my keywords are quality, quantity, and posting tip. Quanitity does not mean google will like you and if you use your keywords too much in any one paragraph (this one is pushing it) then you will get flagged as spamming and it will hurt your google seo.
So when I say post quality and not quantity that refers to good google seo as well! Apply this posting tip to your own blog and if you have free reign on when you post (like this blog) don't post crap when you have nothing of quality to say.