I'm not sure we can worry so much about our first impressions if we want to have lasting impressions. Making a good first impression is great, I just don't think it should be a primary concern on places like a blog.
The problem is that when you write to make a good first impression, you do so at the expense of not creating stronger connections with the people who are already visiting you.
It's a little bit of a challenge to think this way because it's true that on any given day someone new could visit your blog, and whatever article you happened to write is going be their first impression of you. And usually we want to make good first impressions.
I don't think we can have it both ways though.
The alternative is to write in a way where you simply accept that some new visitors will not stick around because you didn't make a great first impression. That's fine. Because what you're doing instead is appreciating the people that have already decided to give you their attention, and strengthening a bond that already exists.
This creates a lasting impression, and when you make a lasting impression with someone they're far more likely to stick with you and be a fan. You may not get as many page views, and you many not have a bunch of mentions on twitter, but I think ultimately it's a much better strategy because the visitors that you do have are likely going to be more passionate about your service or your product.
The opportunity is that most people don't do this.
It's a lot more difficult to measure passion and loyalty than it is to measure page views, clicks, and unique visitors. And since it's easier to measure that's what more people do. They can see the impact some article had, it looks like they're being effective because more people came to their site, and it makes them feel good because there's more immediately tangible evidence of what "worked".
But just because something is easier to measure doesn't mean it's more important. In fact, it's probably the opposite; the harder something is to measure the more valuable it probably is. (I read an article arguing the same thing that I wanted to reference and I can't find it. I'll keep looking.)
I do concern myself with first impressions on my main company website, because part of the reason it exists is to get people to want to learn more about me and my company. My blog however is where I want to make lasting impressions.
Not surprisingly then, I find my blog to be a much bigger asset.