Gather 'round ninjas:
I write in the first person narrative voice because in third person I bore myself. I know that makes no sense at all, and there shouldn't be a reason for it, but that's what happens.
I did an exercise where I wrote in first person and then changed it all to third person—which everyone told me was easy, you just change the pronouns—but I needed to change other words in the sentence too. I found I needed to change 'fun' words to 'boring' words.
I put my aversion to third person narrative down to my science writing training where the third person had to be dry, impersonal and very plain. I decided I could fight this and try to be fun in third person, or take the easier route and write in first person. I'm lazy, I went with first person!
So, after making the discovery I wanted to write in first person, I then needed to learn how to write better in first person. Most writing craft books are all about third person narrative style, especially romance craft writing books. So it was a struggle for me to learn what I was doing wrong because I couldn't understand the examples in third person and how they related to me (did I tell you I've really struggled with this writing thing? I thought it was a natural talent, not something to sweat blood over. How wrong was I?!)
Anyway, I did two things that helped me learn what was missing in my first person writing. I grabbed a book written in first person (one from Keri Arthur’s Riley Jensen series) and I broke down some chapters. How many sentences in each chapter start with "I"? If they don't start with "I", how does she write a sentence? How many different ways does she write sentences? How does she tell us about other people? How do we 'see' the scene? I counted, analysed, scribbled, came up with more questions.
Then I compared it to my writing, and reworked how I wrote so every sentence didn't start with "I".
The whole deep point of view (POV) escaped me too. I thought I was already doing it by writing in first person, while in third person I didn't have a hope. But then I read some Cara McKenna and I realised I wasn't deep at all. Then I landed on some work of Charlotte Stein's and OMG, I had never come across such deep POV—she's totally in the character's head! What a revelation!
So being on a budget, I downloaded samples of every Charlotte Stein book I could. I read each sample back to back so I was immersed in the depth of her characters. Then I went to my writing—which now seemed so shallow it almost made me cry. But I saw how I could make it deeper. I could rewrite bits and add more, and eventually I started "channeling Charlotte" as my critique partner called it.
Then, you know, some of those starts got me hooked and I had to buy a bunch of Charlotte Stein's stories...but that's another thing altogether (an addiction)!
And that's my writing tip. Don't just read craft books. Do whatever will help you to learn the most. I'm someone who learns by doing (and lots of repetition), so the system I described above worked for me. If you like colour, maybe colouring in and highlighting parts of text will work for you (Margie Lawson has a great colouring in system). If you learn by voice, you might read aloud your work and then the work of someone you admire and compare them.
Do whatever works best for you, ninjas.