1. Write a note, in org-mode capture
  2. Insert the YAML frontmatter required for Jekyll weblogs (I use a custom function for this).
  3. Use the org exporter and export the subtree has HTML body-only to a buffer
  4. Save the buffer to [my-blog-directory]/_posts/YYYY-MM-DD-post-title.html
  5. Commit and push

Note: This is the function I use to insert the YAML front matter.

(defun insert-YAML-front-matter (string)
  "Insert \label{ARG} \index{\nameref{ARG}} at point"
  (interactive "sString for \\title: ")
  (insert "#+BEGIN_HTML
---
layout: post
title: " string " 
tags: 
---

#+END_HTML"))

Also note: For convenience I set the org export defaults to subtree-only.

(setq org-export-initial-scope 'subtree)

There does not seem to be a default setting available for body-only.

Sources: