I think start a blog with your name as a domain and write about all the topics that you want as a test, then see which ones get more traffic and focus on only them

I was going to reply, but I think nigelchua covered it very nicely.

Hi hi is there a typo in your "growi'g plant"?

To choose your niche, there are few things to consider:

1) how interested you are (bare min is at least have some interest) which will show in how motivated you will be for mid-long term

2) how monetizable it is eg my passion/skill in shirt ironing, no matter how skilled and pretty my ironed shirts are, limited in terms of monetization I believe

3) search, interest and how big is the niche

4) who are you competitors - determine your market

Etc