Starting back

Hi,
Everyone it has been a long time I had not published any content via a blog or any writing on any social media platform.
I used to be there just by my comments and sharing of the posts.
Earlier when I had started I used to write on my mobile development of ROM I used to compile.
How-tos for the custom ROM, issues related to usage of the same. Opensource software and its usage for our daily computing life. Some of the securities concern and how to make secure of our digital life.
Now once again I would like to start my writings.
With which topic should I start?
Which platform should I pick for regular publishing of my content?