I just write whatever is on my mind. Sometimes I just doodle something or write questions I've been thinking about. How I wish something would be. Sometimes if I feel I learned something important I write it down or if I find a new flower or see a funny looking bird I look it up and write about it. Poems, drawings, feelings descriptions (of places, smells, conversations), dreams, wishes, goals, prayers, achievements, regrets, fantasies, stories, funny situations during the day, misunderstandings. Good ideas I got and lists of all the good things in the day.
If I miss somebody I write about them.
Sometimes I write about myself in a siuation I wish to be or sometimes I write what realy happened that day and then rewrite it into something positive.
If I've had a song on my mind I write it down... Or some math I couldn't do.
Confessions if I've done something bad, a summary of a book or an article I read... anything bassicaly.

I've never been to therapy so I couldn't say anything about that.