A simple way to improve your blog posts is to back up your points with interesting and relevant evidence.
But, there are a ton of old statistics floating about that get referenced again-and-again.
If your reader has seen the same data point referenced in every other blog post they've read, it won't help you build credibility.
You probably don't have the time or the resources to conduct your own market research to come up with new data, so instead, find real examples of businesses/individuals doing whatever you're talking about that prove your point.
For example, if you're talking about landing page conversion rates, add a variety of screenshots from popular companies, and break down their landing page formula.
That's going to be more compelling than a three-year-old data point saying "X% of companies using a benefits-driven headline generated Y% more conversions".