Writing Mysteries

I have always loved mysteries and guessing who did it! One of my favorite Mystery Authors  was Agatha Christie, esp the Herecule  Perot series.  I haven't read a good one in a long time and began reading people I would never thought reading--Mary Higgins Clark and one I never heard of--Joanna Fluke. Both were  seasonal books  and I really needed a book not based around the holidays. I found at the Library a book called The Way of The Guilty...

I have already written a  fifty page mystery which I hope an agent will see it as a Christian Mystery and it  is not based  from a first person point of view. It is called "Serena's Surprise" because  she finds out who is  involved is more than just a criminal.  I decided after completing that one that I would try another Serena Madison story but this time based from another person's point of view--First Person.  I did not know I  should avoid using "I" as much as possible because using "I" like  "It was a hot  July night and I could feel sweat falling down my face. I wondered if the heat would let up.." See the "I"? So  just how many "I" should I avoid?

I am in need of a mentor who is good at that. Someone who can help me craft my story brilliantly that a publisher or agent will no doubt help my book become best seller