Best way to move old blog to new domain name and preserve rankings?

Hello,
I have an old blog that was created two years ago and it has around 15 posts. I recently bought a new domain name that more accurately fits the scope of my content and it also contains a good keyword.

I want to move all the posts over to my new blog, but I want to preserve the rankings.

What’s the best way to achieve this without hurting my current rankings? What is the correct work flow to make this work? Do I mess wtih my .htaccess file?

Thanks for any tips!