I have website (http://www.mymotherknows.blogspot.com) with so many unrelated topics like love, religion, holy spirit, make money online and so many others. now, i am wondering which key words to use, please help me
It's a pointless task. A blog about making money online (you have made money online havn't you? You wouldn't be wasting your time writing about something you don't know anything about, would you) and religion etc etc is fine if it's just a hobby and you don't care too much about traffic. Otherwise, write different blogs on different subjects.
this depends on you .You can use any keyword related to your website theme.i think you should use a high density keyword.
Thank you guys, but, does that mean that i should abandon the blog and create news ones of the same niches?
If you are receiving a decent amount of traffic on the site I wouldn't abandon it, but I would focus on the categories that are most visited. Also, I would set different targeted keywords for each blog post.
It's best to pick a niche - and then find low competition - high traffic keywords for that niche. It's difficult to tell which market you are targeting by the many "themes" you are presenting on your site. It's very difficult to be all things to all people, so try picking a niche, master that market first, then begin thinking about moving on to another. You'll position yourself for greater success if you can narrow your focus and then you'll be able to find the better laser-focused keywords for your site. Best wishes to you, Anita